Dollar

Dollar is a Swift library that provides useful functional programming helper methods without extending any built in objects. It is similar to Lo-Dash or Underscore.js in Javascript.

Cent is a library that extends certain Swift object types using the extension feature and gives its two cents to Swift language. It is now moved into a separate repo to support Swift Package Manager

NOTE: Starting Swift 4 $ is no longer a valid identifier. So you get the following error: '$' is not an identifier; use backticks to escape it . Instead use Dollar.

Contents

• Setup
  • Demo App
• API Documentation
• Usage
  • Array
  • Dictionary
  • Object
  • Function
  • Chaining
• Contributing

Setup

Using cocoapods version 0.36.x or greater

Add pod 'Dollar' to your Podfile and run pod install. Add use_frameworks! to the end of the Podfile. Also checkout this sample app.

Using Swift Package Manager

Add the following dependency .Package(url: "https://github.com/ankurp/Dollar", majorVersion: 7, minor: 1) to your Package.swift file and then run swift build. Requires swift version 2.2 or greater that you can install from https://swift.org

Using git submodule

1. If you are using git then add Dollar as a submodule using git submodule add https://github.com/ankurp/Dollar.git. If not using git download the project using git clone https://github.com/ankurp/Dollar.git in your project folder.
2. Open the Dollar folder. Drag Dollar.xcodeproj, inside the Dollar folder, into the file navigator of your Xcode project.
3. In Xcode, navigate to the target configuration window by clicking on the blue project icon, and selecting the application target under the "Targets" heading in the sidebar.
4. In the tab bar at the top of that window, open the "Build Phases" panel.
5. Expand the "Link Binary with Libraries" group, and add Dollar.framework.
6. In your project file import Dollar and you can call all of the helper functions.

Still stuck. Then checkout this screencast on how to import

Support for Xcode and Swift

• For Xcode 11 (Swift 5.0) use version 9.0.0
• For Xcode 10 (Swift 4.2) use version 8.0.0
• For Xcode 9 (Swift 4) use version 7.1.0
• For Xcode 8 (Swift 3) use version 6.0.0
• For Xcode 7 (Swift 2) use version 4.1.0 or 5.2.0
• For Xcode 6.3 (Swift 1.2) use version 3.0.3
• For Xcode 6.1 and 6.2 (Swift 1.1) use version 2.2.0

Demo Apps

• Using Cocoa Pods
• Using Swift Package Manager
• Using git submodule

Communication

• If you need help, use gitter.im or post a question on Stack Overflow with tag dollar.swift.
• If you'd like to ask a general question, use Stack Overflow.
• If you found a bug, open an issue.
• If you have a feature request, open an issue.
• If you want to contribute, submit a pull request.

Dollar Usage

Array

at - Dollar.at

Creates an array of elements from the specified indexes, or keys, of the collection. Indexes may be specified as individual arguments or as arrays of indexes.

Dollar.at(["ant", "bat", "cat", "dog", "egg"], indexes: 0, 2, 4) 
=> ["ant", "cat", "egg"]

chunk - Dollar.chunk

Creates an array of elements split into groups the length of size. If array can’t be split evenly, the final chunk will be the remaining elements.

Dollar.chunk([1, 2, 3, 4], size: 2)
=> [[1, 2], [3, 4]]

Dollar.chunk([1, 2, 3, 4], size: 3)
=> [[1, 2, 3], [4]]

compact - Dollar.compact

Creates an array with all nil values removed.

Dollar.compact([3, nil, 4, 5]) 
=> [3, 4, 5]

Dollar.compact([nil, nil]) as NSObject[] 
=> []

contains - Dollar.contains

Checks if a given value is present in the array.

Dollar.contains([1, 2, 3, 1, 2, 3], value: 2) 
=> true

Dollar.contains([1, 2, 3, 1, 2, 3], value: 10) 
=> false

cycle - Dollar.cycle

Cycles through the array definetly or indefinetly passing each element into the callback function. The second parameter is to specify how many times to cycle through the array. If left out it will cycle indefinetly.

Dollar.cycle([1, 2, 3], 2) {
  print($0)
}
// Prints the following
123123

difference - Dollar.difference

Creates an array excluding all values of the provided arrays

Dollar.difference([1, 2, 3, 4, 5], [5, 2, 10]) 
=> [1, 3, 4]

each - Dollar.each

Passes each element in the array to the callback

Dollar.each(["A", "B"]) { 
  print("Value \($0)")
}
=> ["A", "B"]

Dollar.each(["A", "B"]) { (index, elem) in
  print("\(index) - \(elem)")
}
=> ["0 - A", "1 - B"]

every - Dollar.every

Checks if the given callback returns true value for all items in the array.

Dollar.every([1, 2, 3, 4], callback: { $0 < 20 }) 
=> true

Dollar.every([1, 2, 3, 4]) { $0 == 1 } 
=> false

factorial Dollar.factorial

Returns factorial of integer

Dollar.factorial(3)
=> 6

Dollar.factorial(0)
=> 1

fetch - Dollar.fetch

Get element from an array at the given index which can be negative to find elements from the end of the array. A default value can be returned if indexing out of bounds.

let arr = [1, 2, 3, 4, 5, 6, 7, 8]
Dollar.fetch(arr, 100)
=> nil

Dollar.fetch(arr, 100, orElse: 42)
=> 42

Dollar.fetch(arr, -1)
=> 8

fill - Dollar.fill

Fills elements of array with value from start up to, but not including, end. This method mutates array.

var arr = Array<Int>(count: 5, repeatedValue: 1)
Dollar.fill(&arr, withElem: 42)
=> [42, 42, 42, 42, 42]

var arr = Array<Int>(count: 5, repeatedValue: 1)
Dollar.fill(&arr, withElem: 42, startIndex: 1, endIndex: 3)
=> [1, 42, 42, 42, 1]

find - Dollar.find

Iterates over elements of an array and returning the first element that the callback returns true for.

Dollar.find([1, 2, 3, 4], callback: { $0 == 2 }) 
=> 2

Dollar.find([1, 2, 3, 4]) { $0 == 10 } 
=> nil

findIndex - Dollar.findIndex

This method is like find except that it returns the index of the first element that passes the callback check.

let arr = [["age": 36], ["age": 40], ["age": 1]]
let result = Dollar.findIndex(arr) { $0["age"] < 20 }
result 
=> 2

findLastIndex - Dollar.findLastIndex

This method is like findIndex except that it iterates over elements of the array from right to left.

let arr = [["age": 36], ["age": 40], ["age": 1]]
let result = Dollar.findLastIndex(arr) { $0["age"] > 30 }
result
=> 1

first - Dollar.first(array: AnyObject[])

Gets the first element in the array.

Dollar.first([1, 2, 3, 4])
=> 1

Dollar.first([]) 
=> nil

groupBy Dollar.groupBy

This method returns a dictionary of values grouped by the value returned by a callback.

Dollar.groupBy([1, 2, 3, 4, 5], callback: {$0 % 2})
=> [0: [2, 4], 1: [1, 3]]

Dollar.groupBy(["strings", "with", "different", lengths"], callback: {$0.characters.count})
=> [7: ["strings", "lengths"], 9: ["different"], 4: ["With"]]

second - Dollar.second(array: AnyObject[])

Gets the second element in the array.

Dollar.second([1, 2, 3, 4])
=> 2

Dollar.second([1]) 
=> nil

Dollar.second([])
=> nil

flatMap - Dollar.flatMap

Maps a function that converts elements to a list and then concatenates them.

let values = [2, 3, 4, 5, 6, 7]
Dollar.flatMap(values) { [$0, $0] }
=> [2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7]

flatMap - Dollar.flatMap

Maps a function that converts a type to an Optional over an Optional, and then returns a single-level Optional.

let url = NSURL(string: "https://apple.com/swift")
Dollar.flatMap(url) { $0.lastPathComponent }
=> Optional("swift")

Note: This is the same behavior as Optional chaining. The code above translates to

NSURL(string: "https://apple.com/swift/")?.lastPathComponent
=> Optional("swift")

flatten - Dollar.flatten

Flattens a nested array of any depth.

Dollar.flatten([[3], 4, 5]) as Int[] 
=> [3, 4, 5]

Dollar.flatten([[3], "Hello", 5]) as NSObject[] 
=> [3, "Hello", 5]

Dollar.flatten([[[3], 4], 5]) as Int[] 
=> [3, 4, 5]

frequencies - Dollar.frequencies

This method returns a dictionary of values in an array mapping to the total number of occurrences in the array. If passed a function it returns a frequency table of the results of the given function on the arrays elements.

Dollar.frequencies(["a", "a", "b", "c", "a", "b"]) 
=> ["a": 3, "b": 2, "c": 1]

Dollar.frequencies([1, 2, 3, 4, 5]) { $0 % 2 == 0 }
=> [false: 3, true: 2]

gcd Dollar.gcd

GCD function return greatest common denominator with number passed

Dollar.gcd(3, 10)
=> 1

Dollar.gcd(3, 9)
=> 3

indexOf - Dollar.indexOf

Gets the index at which the first occurrence of value is found.

Dollar.indexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 1

Dollar.indexOf(["A", "B", "C"], value: "B") 
=> 1

Dollar.indexOf([3, 4, 5], value: 5) 
=> 2

Dollar.indexOf([3, 4, 5], value: 3) 
=> 0

Dollar.indexOf([3, 4, 5], value: 2) 
=> nil

initial - Dollar.initial

Gets all but the last element or last n elements of an array.

Dollar.initial([3, 4, 5]) 
=> [3, 4]

Dollar.initial([3, 4, 5], numElements: 2) 
=> [3]

intersection - Dollar.intersection

Creates an array of unique values present in all provided arrays.

Dollar.intersection([1, 2, 3], [5, 2, 1, 4], [2, 1]) 
=> [1, 2]

it-isIn Dollar.it<T: Comparable>(i: T, isIn range: Range<T>)

Returns true if i is in interval or range

Dollar.it("c", isIn: "a"..."z")
=> true

Dollar.it("z", isIn: "a"..<"z")
=> false

Dollar.it(1, isIn: -1.0...10.0)
=> true

last - Dollar.last

Gets the last element from the array.

Dollar.last([3, 4, 5]) 
=> 5

lastIndexOf - Dollar.lastIndexOf

Gets the index at which the last occurrence of value is found.

Dollar.lastIndexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 4

lcm Dollar.lcm

LCM method return least common multiple with number passed

Dollar.lcm(3, 10)
=> 30

Dollar.lcm(3, 9)
=> 9

rest - Dollar.rest

The opposite of initial this method gets all but the first element or first n elements of an array.

Dollar.rest([3, 4, 5]) 
=> [4, 5]

Dollar.rest([3, 4, 5], numElements: 2) 
=> [5]

map - Dollar.map

Maps each element to new value based on the map function passed

Dollar.map([1, 2, 3, 4]) { 
  $0 * 2
}
=> [2, 4, 6, 8]

min - Dollar.min

Retrieves the minimum value in an array.

Dollar.min([2, 1, 2, 3, 4]) 
=> 1

max - Dollar.max

Retrieves the maximum value in an array.

Dollar.max([1, 2, 3, 4, 2, 1]) 
=> 4

pluck - Dollar.pluck

Retrieves the value of a specified property from all elements in the array.

let arr = [["age": 20], ["age": 30], ["age": 40]]
Dollar.pluck(arr, value: "age") 
=> [20, 30, 40]

pull - Dollar.pull

Removes all provided values from the given array.

Dollar.pull([3, 4, 5, 3, 5], values: 3, 5) 
=> [4]

Dollar.pull([3, 4, 5, 3, 5], values: 4) 
=> [3, 5, 3, 5]

Dollar.pull([3, 4, 5, 3, 5], values: 3, 4, 5) 
=> []

pullAt - Dollar.pullAt

Removes all provided values from the given array at the given indices

let arr = [10, 20, 30, 40, 50]
Dollar.pullAt(arr, indices: 1, 2, 3)

range - Dollar.range

Creates an array of numbers (positive and/or negative) progressing from start up to but not including end.

Dollar.range(4) 
=> [0, 1, 2, 3]

Dollar.range(from: 1, to: 5) 
=> [1, 2, 3, 4]

Dollar.range(from: 0, to: 20, incrementBy: 5) 
=> [0, 5, 10, 15]

Dollar.range(from: 1, through: 5)
=> [1, 2, 3, 4, 5]

Dollar.range(from: 0, through: 20, incrementBy: 5)
=> [0, 5, 10, 15, 20]

reduce - Dollar.reduce

Reduce function that will resolve to one value after performing combine function on all elements

Dollar.reduce([1, 2, 3], initial: 0) { (total, element) in
    total + element
}
=> 6

sample - Dollar.sample

Returns a sample item from the array

let arr : Int[] = [2, 1, 2, 3, 4]
Dollar.contains(arr, value: Dollar.sample(arr))
=> true

sequence - Dollar.sequence

Creates an array of an arbitrary sequence. Especially useful with builtin ranges.

Dollar.sequence(0..4) 
=> [0, 1, 2, 3]

Dollar.sequence(-2.0..2.0) 
=> [-2.0, -1.0, 0.0, 1.0]

Dollar.sequence((0..20).by(5)) 
=> [0, 5, 10, 15]

Dollar.sequence("abc") 
=> ["a", "b", "c"]

remove - Dollar.remove

Removes an element from array.

Dollar.remove(["A", "B", "C", "D"], value: "B")
=> ["A", "C", "D"]

remove - Dollar.remove

Removes all elements from an array that the callback returns true.

let result = Dollar.remove([1, 2, 3, 4, 5, 6]) { 
  $0 == 2 || $0 == 3 
}
result
=> [1, 4, 5, 6]

shuffle - Dollar.shuffle

Shuffles and returns the new shuffled array

let result = Dollar.shuffle([1, 2, 3, 4, 5, 6])
result
=> [4, 1, 3, 5, 6, 2]

size - Dollar.size

Returns size of the array

Dollar.size(["a", "b", "c")
=> 3

sortedIndex - Dollar.sortedIndex

Gives the smallest index at which a value should be inserted into a given the array is sorted.

Dollar.sortedIndex([3, 4, 6, 10], value: 5)
=> 2

Dollar.sortedIndex([10, 20, 30, 50], value: 40)
=> 3

transpose - Dollar.transpose

Creates a tranposed matrix.

Dollar.transpose([[1, 2, 3], [4, 5, 6]])
=> [[1, 4], [2, 5], [3, 6]]

union - Dollar.union

Creates an array of unique values, in order, of the provided arrays.

Dollar.union([1, 2, 3], [5, 2, 1, 4], [2, 1]) 
=> [1, 2, 3, 5, 4]

merge - Dollar.merge

Creates an array of all values, including duplicates, of the arrays in the order they are provided.

let arr  = [1, 5]
let arr2 = [2, 4]
let arr3 = [5, 6]
let result = Dollar.merge(arr, arr2, arr3)
result
=> [1, 5, 2, 4, 5, 6]

uniq - Dollar.uniq

Creates a duplicate-value-free version of an array.

Dollar.uniq([1, 2, 1, 3, 1])
=> [1, 2, 3]

Dollar.uniq([1, 2.5, 3, 1.5, 2, 3.5]) {
  floor($0)
}
=> [1, 2.5, 3]

without - Dollar.without

Creates an array excluding all provided values.

Dollar.without([3, 4, 5, 3, 5], values: 3, 5)
=> [4]

Dollar.without([3, 4, 5, 3, 5], values: 4)
=> [3, 5, 3, 5]

Dollar.without([3, 4, 5, 3, 5], values: 3, 4, 5)
=> []

xor - Dollar.xor

Creates an array that is the symmetric difference of the provided arrays.

Dollar.xor([1, 2, 3], [5, 2, 1, 4])
=> [3, 4, 5]

zip - Dollar.zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays.

Dollar.zip(["fred", "barney"], [30, 40], [true, false]) as [NSObject] 
=> [["fred", 30, true], ["barney", 40, false]]

zipObject - Dollar.zipObject

Creates an object composed from arrays of keys and values.

Dollar.zipObject(["fred", "barney"], values: [30, 40])
=> ["fred": 30, "barney": 40]

partition - Dollar.partition

Produces an array of arrays, each containing n elements, each offset by step. Stops after a partition is less than n length.

let arr = [1, 2, 3, 4, 5]
Dollar.partition(arr, n: 2)
=> [[1, 2], [3, 4]]

Dollar.partition(arr, n: 4, step: 1)
=> [[1, 2, 3, 4], [2, 3, 4, 5]]

Dollar.partition(arr, n: 4, step: 1, pad: nil)
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5]]

Dollar.partition(arr, n: 4, step: 1, pad: [6, 7, 8])
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5, 6]]

partitionAll - Dollar.partitionAll

Produces an array of arrays, each containing n elements, each offset by step. Continues after a partition is less than n length.

Dollar.partitionAll([1, 2, 3, 4, 5], n:4, step: 1)
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5], [4, 5], [5]]

partitionBy - Dollar.partitionBy

Applies a function to each element in array, splitting it each time the function returns a new value.

Dollar.partitionBy([1, 2, 3, 4, 5]) { $0 % 2 == 0 }
=> [[1], [2, 4], [3, 5], [6]]

Dollar.partitionBy([1, 7, 3, 6, 10, 12]) { $0 % 3 }
=> [[1, 7], [3, 6], [10], [12]]

Dictionary

keys - Dollar.keys

Creates an array of keys given a dictionary.

Dollar.keys(["Dog": 1, "Cat": 2])
=> ["Dog", "Cat"]

values - Dollar.values

Creates an array of values given a dictionary

Dollar.values(["Dog": 1, "Cat": 2])
=> [1, 2]

merge - Dollar.merge

Merges all of the dictionaries together and the latter dictionary overrides the value at a given key

let dict: Dictionary<String, Int> = ["Dog": 1, "Cat": 2]
let dict2: Dictionary<String, Int> = ["Cow": 3]
let dict3: Dictionary<String, Int> = ["Sheep": 4]
Dollar.merge(dict, dict2, dict3)
=> ["Dog": 1, "Cat": 2, "Cow": 3, "Sheep": 4]

pick - Dollar.pick

Creates a shallow clone of a dictionary composed of the specified keys.

Dollar.pick(["Dog": 1, "Cat": 2, "Cow": 3], keys: "Dog", "Cow")
=> ["Dog": 1, "Cow": 3]

omit - Dollar.omit

Creates a shallow clone of a dictionary excluding the specified keys.

Dollar.omit(["Dog": 1, "Cat": 2, "Cow": 3, "Sheep": 4], keys: "Cat", "Dog")
=> ["Cow": 3, "Sheep": 4]

Object

tap - Dollar.tap

Invokes interceptor with the object and then returns object.

var beatle = Car(name: "Fusca")
Dollar.tap(beatle, {$0.name = "Beatle"}).color = "Blue"

Function

after - Dollar.after

Creates a function that executes passed function only after being called n times.

var saves = ["profile", "settings"];
let asyncSave = { (function: () -> ()?) in
   function() 
   // Saving right away for testing 
   // but in real world would be async
}
var isDone = false
var completeCallback = Dollar.after(saves.count) {
   isDone = true
}
for elem in saves {
   asyncSave(completeCallback)
}
isDone 
=> true

bind - Dollar.bind

Creates a function that, when called, invokes func with the binding of arguments provided.

var helloWorldFunc = Dollar.bind({(T...) in
  T[0] + " " + T[1] + " from " + T[2] 
}, "Hello", "World", "Swift")
helloWorldFunc() 
=> "Hello World from Swift"

helloWorldFunc = Dollar.bind({ $0 + " World" }, "Hello")
helloWorldFunc()
=> "Hello World"

helloWorldFunc = Dollar.bind({ $0 + $1 + " World" }, "Hello ", "Great")
helloWorldFunc()
=> "Hello Great World"

compose - Dollar.compose

Compose two or more functions where the return value of the first function is passed into the next function. Useful when chaining functions and returns a function that can be called with variadic argument values or an array of values as input

let double = { (params: Int...) -> [Int] in
  return Dollar.map(params) { $0 * 2 }
}
let subtractTen = { (params: Int...) -> [Int] in
  return Dollar.map(params) { $0 - 10 }
}
let doubleSubtractTen = Dollar.compose(double, subtractTen)
doubleSubtractTen(5, 6, 7)
=> [0, 2, 4]

let f = Dollar.compose({ (arr: [Int]) -> [Int] in
  Dollar.map(arr) { $0 + 1 }
}, { (arr: [Int]) -> [Int] in
  Dollar.map(arr) { $0 * 2 }
})
f([1, 2])
=> [4, 6]

curry - Dollar.curry

Returns a function which when invoked either executes the function returning its result, if all function arguments have been provided, or returns another function that accepts one more argument of the remaining function arguments until all arguments are supplied. This is useful for making partial function as seen in these examples.

func adder(x: Int, y: Int, z: Int) -> Int {
return x + y + z
}

let curriedAdder = Dollar.curry(adder)
let addTenAnd = curriedAdder(10)
let addThirtyAnd = addTenAnd(20)
addThirtyAnd(1)
=> 31

addThirtyAnd(50)
=> 80

addTenAnd(10)(10)
=> 30

id - Dollar.id

The identify function which simply returns the argument its given.

Dollar.id("Hello World from Swift")
=> "Hello World from Swift"

memoize - Dollar.memoize

Returns a memoized function to improve performance by caching recursive function values.

var times = 0 // to test memoization

let fibMemo = Dollar.memoize { (fib: (Int -> Int), val: Int) -> Int in
  times += 1
  return val == 1 || val == 0 ? 1 : fib(val - 1) + fib(val - 2)
}

let x = fibMemo(5)
times
=> 6

times = 0
let y = fibMemo(5)
times
=> 0

times = 0
let z = fibMemo(6)
times
=> 1

noop - Dollar.noop

A no-operation function.

Dollar.noop() 
=> nil

now - Dollar.now

Gets the number of seconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).

Dollar.now() 
=> 1431911564.292577

once - Dollar.once

Get a wrapper function that executes the passed function only once. Useful for getting shared config or creating singleton objects.

func createConfig() -> [String: String] {
  var i = 1
  return [
    "App ID": "\(i++)",
    "URL": "https://someurl"
  ]
}

let getConfig = Dollar.once(createConfig)
getConfig()
=> ["App ID": "1", "URL": "https://someurl"]

getConfig()
=> ["App ID": "1", "URL": "https://someurl"]

partial - Dollar.partial

Creates a function that, when called, invokes func with any additional partial arguments prepended to those provided to the new function.

let partialFunc = Dollar.partial({(T...) in 
  T[0] + " " + T[1] + " from " + T[2] 
}, "Hello")
partialFunc("World", "Swift") 
=> "Hello World from Swift"

times - Dollar.times

Call a function n times and also passes the index. If a value is returned in the function then the times method will return an array of those values.

let fun = Dollar.bind({ (names: String...) -> String in
   let people = Dollar.join(names, separator: " from ")
   return "Hello \(people)"
   }, "Ankur", "Swift")
Dollar.times(2, function: fun) as String[] 
=> ["Hello Ankur from Swift", "Hello Ankur from Swift"]

Chaining

Dollar.chain(...)

any

Returns true if callback function returns true for at least one element in the array

var chain = Dollar.chain([1, 2, 3])
chain.any({ ($0 as Int) < 2 })
=> true

all

Returns true if callback function returns true for all elements in the array

var chain = Dollar.chain([1, 2, 3])
chain.all({ ($0 as Int) < 10 })
=> true

each

Passes each element value to the callback function

var chain = Dollar.chain(["Hello", "World"])
var strBuilder = ""
chain.each({ strBuilder += ($0 as String) }).value
strBuilder
=> "HelloWorld"

filter

Filters the arrary to elements for which the callback function returns true

var chain = Dollar.chain([1, 2, 3, 4])
chain.filter({ ($0 as Int) < 3 }).value
=> [1, 2]

first

Returns the first element in the array and terminates the chain

var chain = Dollar.chain([1, 2, 3, 4])
chain.first()
=> 1

second

Returns the second element in the array and terminates the chain

var chain = Dollar.chain([1, 2, 3, 4])
chain.second()
=> 2

third

Returns the third element in the array and terminates the chain

var chain = Dollar.chain([1, 2, 3, 4])
chain.third()
=> 3

flatten

Flattens a nested array of any depth.

var chain = Dollar.chain([[1, [2]], [3], 4])
chain.flatten().value
=> [1, 2, 3, 4]

initial

Gets all but the last element or last n elements of an array.

var chain = Dollar.chain([1, 2, 3, 4])
chain.initial(2).value
=> [1, 2]

map

Maps each element to the new value returned in the callback function

var chain = Dollar.chain([1, 2, 3, 4])
chain.map({ ($0 as Int) * 2 }).value
=> [2, 4, 6, 8]

size

Returns size of the array and terminates the chain

var chain = Dollar.chain([1, 2, 3, 4])
chain.map({ ($0 as Int) * 2 }).size()
=> 4

slice

Slices the array based on the start and end position. If an end position is not specified it will slice till the end of the array.

var chain = Dollar.chain([1, 2, 3, 4, 5, 6, 7])
chain.slice(2, end: 4).value
=> [3, 4]

value

Returns the value after evaluating all callbacks

var chain = Dollar.chain([1, 2, 3, 4, 5, 6, 7])
chain.value
=> [1, 2, 3, 4, 5, 6, 7]

Chaining more than one method

Dollar.chain([[1, 2], 3, [[4], 5]])
  .initial()
  .flatten()
  .first()
=> 1

Dollar.chain([1, 2, 3, 4, 5])
  .filter { $0 % 1 == 0 }
  .map { $0 * 2 }
  .all {$0 < 10}
=> false

Dollar.chain([1, 2, 3, 4, 5])
  .map({ $0 * 2 })
  .flatten()
  .initial(2).value
=> [2, 4, 6]

Cent Usage

Array Extensions

<< elem: Element -> [Element]

Overloaded operator to append element to an array or append elements from another array into the first array. Return array with the element appended in the end.

var array = [1, 2, 3]
array << 4
=> [1, 2, 3, 4]
array << [5, 6]
=> [1, 2, 3, 4, 5, 6]

at(indexes: Int...) -> [Element]

Creates an array of elements from the specified indexes, or keys, of the collection.

let array = ["foo", "spam", "bar", "eggs"]
let some = array.at(1, 3)
=> ["spam", "eggs"]

each(callback: (Element) -> ()) -> [Element]

For each item in the array invoke the callback by passing the elem

let array = ["foo", "spam", "bar", "eggs"]
array.each {
  print($0)
}
=> ["foo", "spam", "bar", "eggs"]

eachWithIndex(callback: (Int, Element) -> ()) -> [Element]

For each item in the array invoke the callback by passing the elem along with the index

let array = ["foo", "spam", "bar", "eggs"]
array.each { (index, elem)
  print("\(index) - \(elem)")
}
=> ["foo", "spam", "bar", "eggs"]

cycle<U>(times: Int, callback: (Element) -> U)

Cycles through the array definetly or indefinetly passing each element into the callback function. The second parameter is to specify how many times to cycle through the array. If left out it will cycle indefinetly.

[1, 2, 3].cycle(2) {
  print($0)
}
// Prints the following
123123

[1, 2, 3].cycle {
  print($0)
}
// Cycles in an infinite loop

every(callback: (Element) -> Bool) -> Bool

Checks if the given callback returns true value for all items in the array.

["angry", "hungry"].every { (a: String) -> (Bool) in 
  a.hasSuffix("gry") 
}
=> true

indexOf<T: Equatable>(value: T) -> Int

Gets the index at which the first occurrence of value is found.

let array = ["foo", "spam", "bar", "eggs"]
array.indexOf("spam")
=> 1
array.indexOf("None")
=> nil

fetch(index: Int, orElse: T? = .None) -> T!

Get element from an array at the given index which can be negative to find elements from the end of the array. A default value can be returned if indexing out of bounds.

let arr = [1, 2, 3, 4, 5, 6, 7, 8]
arr.fetch(100)
=> nil

arr.fetch(100, orElse: 42)
=> 42

arr.fetch(-1)
=> 8

findIndex(callback: (Element) -> Bool) -> Int?

This method is like find except that it returns the index of the first element that passes the callback check.

let ind: int? = ["foo", "bar", "spam", "eggs"].findIndex {
  $0.length == 4
}
ind! == 2 
=> true

findLastIndex(callback: (Element) -> Bool) -> Int?

This method is like findIndex except that it iterates over elements of the array from right to left.

let ind: int? = ["foo", "bar", "spam", "eggs"].findLastIndex {
  $0.length == 4 
}
ind! == 3 
=> true

first() -> Element?

Gets the first element in the array.

let first = ["foo", "bar"].first()
=> "foo"

flatten() -> [Element]

Flattens a nested array of any depth.

let unFlattened = ["foo", ["bar"], [["spam"]], [[["eggs"]]] ]
let flattened = unFlattened.flatten() 
=> ["foo", "bar", "spam", "eggs"]

get(index: Int) -> Element?

Get element at index

let element = ["foo", "bar"].get(0)
element!
=> "foo"

let nothing = ["foo", "bar"].get(1000)
=> nil

initial(numElements: Int? = 1) -> [Element]

Gets all but the last element or last n elements of an array.

let initial = ["foo", "bar", "spam"].initial(2) 
=> ["foo"]

last() -> Element?

Gets the last element from the array.

let last = ["foo", "bar"].last() 
=> "bar"

rest(numElements: Int? = 1) -> [Element]

The opposite of initial this method gets all but the first element or first n elements of an array.

let rest = ["foo", "bar", "spam"].rest(2)
=> ["spam"]

min<T: Comparable>() -> T?

Retrieves the minimum value in an array.

let min = [ 0, 1, 2 ].min()
=> 0

max<T: Comparable>() -> T?

Retrieves the maximum value in an array.

let max = [ 0, 1, 2].max()
=> 2

remove<T: Equatable>(value: T) -> T?

Remove element from array

var arr = ["A", "B", "C", "D", "E"]
arr.remove("B")
=> ["A", "C", "D", "E"]

contains<T:Equatable>(value: T) -> Bool

Checks if a given value is present in the array.

var arr = ["A", "B", "C", "D", "E"]
arr.contains("C")
=> true
arr.contains("Z")
=> false

Character Extensions

"A".description -> String

Get string description of Character

let ch: Character = "A"
let str = ch.description
=> "A"

"A".ord -> Int

Get int representation of character

Character("A").ord
=> 65

Date Extensions

Date.from(#year: Int, month: Int, day: Int) -> NSDate

Returns a new Date given the year month and day

let date = Date.from(2014, 1, 1) 
=> "Jan 1, 2014, 12:00 AM"

Date.from(#unix: Double) -> NSDate

Returns a new Date given the unix timestamp (timeIntervalSince1970)

let date = Date.from(unix: 1_388_552_400.0)
=> "Jan 1, 2014, 12:00 AM"

Date.parse(dateStr: String, format: String = "yyyy-MM-dd") -> NSDate

Parses the date based on the format and return a new Date

let parsedDate = Date.parse("2014-01-01", format: "yyyy-MM-dd")
=> "Jan 1, 2014, 12:00 AM"

Date.unix(date: NSDate = NSDate()) -> Double

Returns the unix timestamp of the date passed in or the current unix timestamp

let currentUnix = Date.unix()
=> 1,388,552,400.0

var otherNSDate = Date()
let otherUnix = Date.unix(otherDate)
=> 1,388,552,400.0

Int.hour.fromNow et al.

Use the following syntax to calculate dates and times based on the user's current calendar.

1.day.ago
=> "Apr 10, 2015, 11:51 AM"
4.hours.fromNow
=> "Apr 11, 2015, 3:51 PM"

Dictionary Extensions

merge<K, V>(dictionaries: Dictionary<K, V>...)

Merges the dictionary with dictionaries passed. The latter dictionaries will override values of the keys that are already set

var dic = ["foo": "bar"] 
let anotherDic = ["foo": "baz", "spam": "eggs"]
dic.merge(anotherDic)
=> ["foo": "baz", "spam": "eggs"]

Int Extensions

times(callback: (Int) -> ())

Invoke a callback n times with callback that takes index

5.times { print("Na") } 
=> "NaNaNaNaNa"

times (function: () -> ())

Invoke a callback n times

5.times { (a: Int) -> () in print("\(a) ") } 
=> 0 1 2 3 4  

char -> Character

Get ASCII character from integer

65.char
=> "A"

isEven

Check if int is even

2.isEven
=> true

1.isEven
=> false

isOdd

Check if int is odd

3.isOdd
=> true

2.isOdd
=> false

digits() -> [Int]

Splits the int into array of digits

4208.digits()
=> [4, 2, 0, 8]

lcm() -> Int

LCM method return least common multiple with number passed

3.lcm(10)
=> 30

3.lcm(9)
=> 9

gcd() -> Int

GCD method return greatest common denominator with number passed

3.gcd(10)
=> 1

3.gcd(9)
=> 3

random() -> Int

Returns random number from 0 upto but not including value of integer

3.random()
=> 2

3.random()
=> 1

factorial() -> Int

Returns factorial of integer

3.factorial()
=> 6

0.factorial()
=> 1

isIn(interval) -> Bool

Returns true if i is in interval or range

5.isIn(1...10)
=> true

10.isIn(1..<10)
=> false

next() -> Int

Get the next int

10.next()
=> 11

prev() -> Int

Get the previous int

10.prev()
=> 9

upTo(limit: Int, callback: () -> ())

Invoke the callback from int up to and including limit

3.upTo(5) {
  print("Hi")
}
Prints "HiHiHi"

downTo(limit: Int, callback: () -> ())

Invoke the callback from int down to and including limit

3.downTo(0) {
  print("Hi")
}
Prints "HiHiHiHi"

String Extensions

.length

Get the length of the string

"Hello".length
=> 5

.camelCase

Get the camel case representation of the string

"__Dollar and cent-- dollarANDCent".camelCase
=> "dollarAndCentDollarAndCent"

.kebabCase

Get the kebab case representation of the string

"__Dollar and cent-- dollarANDCent".kebabCase
=> "dollar-and-cent-dollar-and-cent"

.snakeCase

Get the snake case representation of the string

"__Dollar and cent-- dollarANDCent".snakeCase
=> "dollar_and_cent_dollar_and_cent"

.startCase

Get the start case representation of the string

"__Dollar and cent-- dollarANDCent".startCase
=> "Dollar And Cent Dollar And Cent"

=~ str: String -> Bool

Does a regex match of whether regex string on the right is matches the string on the left

"Dollar" =~ "oll"
=> true

* n: Int -> String

Get string concatenated n times

"Hi Swift! " * 3
=> "Hi Swift! Hi Swift! Hi Swift! "

[i: Int] -> Character?

Get character at a subscript

"Hello World"[6] == "W"
=> true

"Hi"[5]
=> nil

[str: String] -> String?

Returns the substring based on the first regex match passed in the subscript

let proj = "Dollar and Cent"
proj["^.+[^and Cent]"]
=> {Some: "Dollar"}

[r: Range<Int>] -> String

Get substring using subscript notation and by passing a range

"Hello World"[0..<5] == "Hello" 
=> true

indexOf(char: Character) -> Int?

Get the start index of character

"hello world".indexOf(Character("o"))!
=> 4

indexOf(str: String) -> Int?

Get the start index of string

"hello world".indexOf("llo")!
=> 2

"hello world".indexOf("illo")
=> nil

indexOf(pattern: String) -> Int?

Get the start index of regex pattern inside the string

"hello world".indexOf(".llo")!
=> 1

split(delimiter: Character) -> [String]

Get an array from string split using the delimiter character

"Hello World".split(" ") 
=> ["Hello", "World"]

lstrip() -> String

Get string without leading spaces

let leadingSpace = "  Hello"
leadingSpace.lstrip()
=> "Hello"

rstrip() -> String

Get string without trailing spaces

let trailingSpace = "Hello   "
trailingSpace.rstrip()
=> "Hello"

strip() -> String

Get string without leading or trailing spaces

let spaces = "   Hello   "
spaces.strip()
=> "Hello"

Regex

init

Init with regex pattern as string

Regex.init("^Hello.World$") // Regex that matches "Hello World"

matches(testStr: String) -> [AnyObject]

Return matches based on String passed.

let re = Regex.init("^Hello.World$")
re.matches("Hello World")

test(testStr: String) -> Bool

let re = Regex.init("^Hello.World$")
re.test("Hello World")
=> true

re.test("Str")
=> false

escapeStr(str: String) -> String

Escape string with regex characters

Regex.escape("Hello.World")
=> "Hello\.World"

Range Extensions

equals - ==

Check the equality of two ranges

(1...5) == (1...5) 
=> true

(1..<5) == (1...5) 
=> false

eachWithIndex(callback: (T) -> ())

For each index in the range invoke the callback by passing the item in range

(1...5).eachWithIndex { (a: Int) -> () in print("\(a)") } 
=> 12345

each(callback: () -> ())

For each index in the range invoke the callback

(1...5).each { print("Na") } 
=> "NaNaNaNaNa"

Contributing

If you are interested in contributing checkout CONTRIBUTING.md