An NSPredicate DSL for iOS, OSX, tvOS, & watchOS. Inspired by SnapKit and lovingly written in Swift.

Last update: Jun 25, 2022

Pretty Banner Travis Build Status Coveralls Supported Platforms Swift Version Compatibility Cocoapods Version Carthage Compatible LICENSE

PrediKit

A Swift NSPredicate DSL for iOS & OS X inspired by SnapKit, lovingly written in Swift, and created by that weird dude at KrakenDev.

If you're familiar with the intuitive feel of the SnapKit API, then you'll feel right at home with PrediKit! 💖

Documentation

Documentation is generated by Jazzy and can be found here for your convenience!

Why create PrediKit?

Because I wanted to! Also, because NSPredicate creation is hard. When working with CoreData you use NSPredicates to fetch persisted objects. CoreData is hard enough, so why have the additional complexity of using a complex string-based predicate system?

The language you need to use to create predicate formats are completely string-based which can lead to a host of issues:

  • We have a tendency to misspell words and with the current system, you can build and run without ever knowing you misspelled a property name...until it's too late.
  • For many an iOS/OSX developer (myself included), they may be very unfamiliar with the SQL-like language that comes with the creation of predicate formats. In fact, an entire cheatsheet by the awesome guys at Realm was created because of this!
  • With complex predicate creation, it's easy to get string-blindness. Go ahead...try creating a complex predicate and reading it after a couple of hours. I dare you. 😎
  • If you misspell a property key name in a predicate format string but the string is parseable by the NSPredicate system, then nothing happens. It just fails silently. At least, I think it does. I'm currently writing this on 2 hours of sleep. Don't quote me on that.

What does it fix?

Well, hopefully it fixes all of the above and more. Currently, it:

  • Gives the developer a closure based way to create NSPredicates.
  • It also, through the magic of Xcode, gives you a way to autocomplete your queries. No more referencing a cheatsheet. Just hit the dot button and enjoy the autocomplete.
  • I also carefully constructed the API to read as much like a book as possible. Matching strings even have a redundant API just to be grammatically correct when specifying if a string matches or doesNot.match another value.
  • Through a little runtime-magic/reflection, PrediKit will crash at runtime if you misspell a property key or supply a property key that does not exist in a specific class' property list.
  • All predicate builder closures do not need capture semantics as each closure is a @noescape closure. Read here if you don't know what that means 🤓 .

Installation

PrediKit can be included in your project through any of these methods:

CocoaPods

CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ gem install cocoapods

CocoaPods 0.39.0+ is required to build PrediKit

To integrate PrediKit through CocoaPods, make sure the use_frameworks! line is included in your Podfile (PrediKit is written in Swift so it needs to be brought in as a framework). Make sure these lines are somewhere in your Podfile:

use_frameworks!
#for the latest version that is compatible with Swift 4.2 use:
pod 'PrediKit'
#for the latest version that is compatible with legacy Swift 2.3 use this instead:
pod 'PrediKit', :git => 'https://github.com/KrakenDev/PrediKit.git', :branch => 'swift2.3'
#for the latest version that is compatible with legacy Swift 2.1 use this instead:
pod 'PrediKit', :git => 'https://github.com/KrakenDev/PrediKit.git', :branch => 'swift2.1'

Then, run the following command:

$ pod install

Afterwards, whenever you need PrediKit, add this line to the top of the file it's being used in:

import PrediKit

Carthage

Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.

You can install Carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

To integrate PrediKit into your Xcode project using Carthage, specify it in your Cartfile:

github "KrakenDev/PrediKit"

For legacy swift versions, I am keeping the swift2.1 && swift2.3 branches open for you. However, no more dev will be done for them (I will however, happily accept pull requests for any feature I happen to add!) If you are using these legacy versions, you should be able to use this instead in your Cartfile:

github "KrakenDev/PrediKit" "swift2.1"
github "KrakenDev/PrediKit" "swift2.3"

Run carthage update to build the framework and drag the built PrediKit.framework into your Xcode project.

Afterwards, whenever you need PrediKit, add this line to the top of the file it's being used in:

import PrediKit

Manually

If you prefer not to use either of the aforementioned dependency managers, you can integrate PrediKit into your project manually.

First, copy and paste these commands into Terminal:

git clone https://github.com/KrakenDev/PrediKit.git
open PrediKit/Sources/

This should open a Finder window with the important files needed for PrediKit located in the Sources folder of the repo. Drag these folders into your project (preferable in a folder named "PrediKit") and code away! Since you would be copying these files into your project directly, there is no need for the import PrediKit line in any of the files that you need it.

The downside to this is that you can not update PrediKit easily. You would need to repeat these steps each time you wanna grab the latest and greatest! 😱

Usage

PSA: IF YOU HATE STRINGLY TYPED APIs LIKE I DO, THEN CHECK OUT THE SECTION ON SWIFT 3's #keyPath() AT THE BOTTOM OF THE README!!!

PrediKit tries to make NSPredicate creation easy. Heavily inspired by SnapKit's API, the API for PrediKit is extremely similar for people who love it as much as I do. Check it out. This example creates a predicate used to fetch a ManagedObject from CoreData:

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string("title").equals("The Almighty Kraken")
}

To check if a property is nil:

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string("title").equalsNil()
}

PrediKit can also query member properties. Say you have a class structure like this:

class Captain: NSObject {
    var name: String
}
class Ship: NSObject {
    var captain: Captain
}

And you want to create these predicates:

let someCaptain = Captain()
NSPredicate(format: "captain == %@ && captain.name == 'Chief Supreme'", someCaptain)

Creating the above with PrediKit is easy and expressive:

let someCaptain = Captain()
let predicate = NSPredicate(Ship.self) { includeIf
    let includeIfShipCaptain = includeIf.member("captain", ofType: Captain.self)
    includeIfShipCaptain.equals(someCaptain) &&
    includeIfShipCaptain.string("name").equals("Chief Supreme")
}

PrediKit also overloads the &&, ||, and ! operators. This allows you compound and specify whether or not to include your includers (Crappy name, I know. Feel free to give me suggestions).

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    //Include any ManagedLegend instance if the property named "string" is NOT nil and does NOT equal "The Almighty Kraken"
    !includeIf.string("title").equalsNil() &&
    !includeIf.string("title").equals("The Almighty Kraken") &&

    //Also include any ManagedLegend instance if the date property named "birthdate" is in the past or if the bool property "isAwesome" is true.
    includeIf.date("birthdate").isEarlierThan(NSDate()) ||
    includeIf.bool("isAwesome").isTrue()
}

You can even create includers conditionally!

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    let isKrakenQuery = includeIf.string("title").equals("The Almighty Kraken")
    let birthdateQuery = includeIf.date("birthdate").isEarlierThan(NSDate())
    let isAwesomeQuery = includeIf.bool("isAwesome").isTrue

    if shouldCheckBirthdate {
        (isKrakenQuery && birthdateQuery) || isAwesomeQuery
    } else {
        isKrakenQuery || isAwesomeQuery
    }
}

I don't know about y'all, but the SQL-like IN operator was hard to wrap my head around. PrediKit makes this a little more human-readable:

let awesomePeeps = ["Kraken", "Cthulhu", "Voldemort", "Ember", "Umber", "Voldemort"]
let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string("title").matchesAnyValueIn(awesomePeeps)
}

PrediKit also has built-in support for subquery predicates:

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string("title").equals("The Almighty Kraken") &&

    //Only include Krakens that have more than three hungry cerberus friends
    includeIf.collection("cerberusFriends").subquery(ManagedCerberus.self) {
        $0.bool("isHungry").isTrue()
        return .IncludeIfMatched(.Amount(.IsGreaterThan(3)))
    }
}

#keyPath() + PrediKit = 💖

PrediKit becomes MUCH more expressive and safer when using Swift 3's #keyPath syntax. I don't know about you but I HATE stringly typed APIs. The best part of #keyPath is that you get autocompletion of your properties and a way to get sub properties without using PrediKit's .member functions:

let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string(#keyPath(ManagedLegend.title)).equals("The Almighty Kraken")
}
let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string(#keyPath(ManagedLegend.bestFriend.title)).equals("The Cool Elf")
}

Selector Extension Pattern Variation

Personally, I love using a variation of the Selector Extension Pattern when using PrediKit. It allows you to avoid misspelling your property names when using the API. It also allows you to rename your keypath properties at will. By renaming, every instance of that keyPath used by PrediKit should give you a compiler error so you don't miss a beat and can feel safe knowing you haven't missed any property names in a name change refactor. By creating a String extension like so:

import Foundation

extension String {
    static let title = #keyPath(Kraken.title)
    static let birthdate = #keyPath(Kraken.birthdate)
    static let age = #keyPath(Kraken.age)
    static let friends = #keyPath(Kraken.friends)
    static let isAwesome = #keyPath(Kraken.isAwesome)
    static let isHungry = #keyPath(Kraken.isHungry)
}

PrediKit becomes a lot more expressive now:

//BEFORE
let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string(#keyPath(ManagedLegend.title)).equals("The Almighty Kraken")
}
//AFTER
let predicate = NSPredicate(ManagedLegend.self) { includeIf in
    includeIf.string(.title).equals("The Almighty Kraken")
}

LICENSE

PrediKit is licensed under the MIT license. Check out the LICENSE file to learn more.

GitHub

https://github.com/KrakenDev/PrediKit
Comments
  • 1. Builder needs method for querying object properties

    Case where we want to query an object with related objects, such as:

    class Captain: NSObject {
        var name: String
    }
    class Ship: NSObject {
        var captain: Captain
    }
    NSPredicate(format: "captain == %@", someCaptain)
    NSPredicate(format: "captain.name == 'Chief Supreme'")
    

    There currently is no method to match an object property (example 1), or to match a related object's property (example 2).

    Are there currently any plans for this?

    Reviewed by djbe at 2016-05-23 17:24
  • 2. Parameters are bound to the wrong field

    Let's say I have the following code:

    let predicate = NSPredicate(Shipment.self) { includeIf in
        let includeIfState = includeIf.member(Selector(ShipmentRelationships.currentState.rawValue), ofType: State.self).string(Selector(StateAttributes.stateRaw.rawValue))
    
        let noOffer = includeIf.member(Selector(ShipmentRelationships.acceptedOffer.rawValue), ofType: Offer.self).equalsNil
        let cancelled = includeIfState.equals(State.State.Cancelled.rawValue)
        let expired = includeIf.number(Selector(ShipmentAttributes.pickupTimeTo.rawValue)).isLessThanOrEqualTo(soon)
        let sender = includeIf.member(Selector(ShipmentRelationships.sender.rawValue), ofType: Sender.self).equals(data)
    
        sender && noOffer && !cancelled && !expired
    }
    

    Unexpectedly, the resulting predicate is something like this:

    sender == 1464553718.353965 AND acceptedOffer == nil AND (NOT currentState.stateRaw == "cancelled") AND (NOT pickupTimeTo <= <Sender: 0x7fe2cb708720> (entity: Sender; id: 0xd000000000080000 x-coredata://F5039107-C745-4046-B0B5-5F71ED5738B7/Sender/p2 ; data: {...}))

    As you can see, the parameters of the sender and expired sub-predicates have been exchanged.

    Side note: I'm using variables inside the block because this is a simplified example. In the actual code, the final predicate is composed of different sub-predicates depending on some filter parameter.

    Reviewed by djbe at 2016-05-29 20:28
  • 3. Minimal iOS version that PreditKit supports

    I used PrediKit in two projects installed through CocoaPods.

    In my new one I used Carthage and now XCode throws an error: Module file's minimum deployment target is ios8.3 v8.3: .../Carthage/Build/iOS/PrediKit.framework/Modules/PrediKit.swiftmodule/i386.swiftmodule

    What I'm doing wrong or did in my previous two projects?

    Reviewed by av0c0der at 2016-07-08 21:25
  • 4. Correct the spelling of CocoaPods in README

    This pull request corrects the spelling of CocoaPods 🤓 https://github.com/CocoaPods/shared_resources/tree/master/media

    Created with cocoapods-readme.

    Reviewed by ReadmeCritic at 2016-05-18 14:00
  • 5. Swift 4.2 Compilation errors trying to build in Debug

    In the latest swift migration there are two lies of code in #IF DEBUG blocks that weren't migrated along with the rest. This causes compilation errors when trying to build in debug.

    I have the fix done locally for normal development, but it would be nice to fix for first pod installs and the like.

    The problems are in MemberQuery.swift on line 48 and PredicateBuilder.swift on line 150. Both require changing String(type) to String(describing: type)

    Reviewed by NerdBird at 2019-02-21 01:48
  • 6. Xcode 10, Swift 4.2 update

    Update the project to use Xcode 10 and Swift 4.2

    Updating pod version to 4.2 (not very sure how versioning is maintained for this project, probably synced with Swift version)

    There was some compilation issue also with the project due to the new build system, for that, I have to remove copy phase (watchOS and tvOS Info.plist copy) to iOS and OSX target.

    Also Bool argument converting to CVarArgs crash as they give nil, so using NSNumber(value: bool) for boolean parameter in NSPredicate initializer.

    Let me know in case any other modification is required for this PR to be merged. Thanks

    Reviewed by aksswami at 2018-10-16 07:59
  • 7. Consider creating a new release now that Swift 4 support has been added

    Just a house keeping issue...since a new release wasn't created when Swift 4 support was added back in May, integrating with CocoaPods requires referencing the master branch or the Swift 4 commit.

    Reviewed by gcox at 2018-07-31 16:47
  • 8. Installed in CocoaPods and having compile issues

    Hello, I installed it, and while running it in Swift 4.2, I keep getting the following error. I get it on both MemberQuery.swift and PredicateBuilder.swift

    /Pods/PrediKit/Sources/Queries/MemberQuery.swift:48:26: Cannot invoke initializer for type 'String' with an argument list of type '(T.Type)'

    Please Help!

    Reviewed by chadbrochill317 at 2019-07-19 19:23
  • 9. Remove default implementation Reflectable for NSObject

    Hi, I use your nice PrediKit to filter realm Results, works pretty good, but needs particular implementation of the properties() method My variant:

    extension Object: Reflectable {
        public static func properties() -> [Selector] {
            guard let schema = self.sharedSchema() else { return [] }
            let properties = schema.properties.map {
                Selector($0.name)
            }
    
            let computedProperties = schema.computedProperties.map {
                Selector($0.name)
            }
    
            return properties+computedProperties
        }
    }
    

    Problem is the following: Object inherited from NSObject, so I can't override your implementation in the NSObject extension

    Reviewed by kolbasek at 2019-05-24 09:10
Related tags
Super awesome Swift minion for Core Data (iOS, macOS, tvOS)

⚠️ Since this repository is going to be archived soon, I suggest migrating to NSPersistentContainer instead (available since iOS 10). For other conven

Jan 29, 2022
Simple IOS notes app written programmatically without storyboard using UIKit and CoreData
Simple IOS notes app written programmatically without storyboard using UIKit and CoreData

Notes Simple Notes app. Swift, UIKit, CoreData Description Simple IOS notes app

Mar 22, 2022
CloudCore is a framework that manages syncing between iCloud (CloudKit) and Core Data written on native Swift.
CloudCore is a framework that manages syncing between iCloud (CloudKit) and Core Data written on native Swift.

CloudCore CloudCore is a framework that manages syncing between iCloud (CloudKit) and Core Data written on native Swift. Features Leveraging NSPersist

Jun 23, 2022
iOS app built with UIKit and programatic auto-layouts to learn and apply knowledge. Offline storage using CoreData and Caching

PurpleImage Search Pixabay for images and save them offline to share and view To use: Clone the GitHub project, build and run in Xcode. The API is com

May 10, 2022
🎯 PredicateKit allows Swift developers to write expressive and type-safe predicates for CoreData using key-paths, comparisons and logical operators, literal values, and functions.
🎯 PredicateKit allows Swift developers to write expressive and type-safe predicates for CoreData using key-paths, comparisons and logical operators, literal values, and functions.

?? PredicateKit PredicateKit is an alternative to NSPredicate allowing you to write expressive and type-safe predicates for CoreData using key-paths,

Jun 17, 2022
Feb 13, 2022
Robust CloudKit synchronization: offline editing, relationships, shared and public databases, field-level deltas, and more.
Robust CloudKit synchronization: offline editing, relationships, shared and public databases, field-level deltas, and more.

CloudCore CloudCore is a framework that manages syncing between iCloud (CloudKit) and Core Data written on native Swift. Features Leveraging NSPersist

Jun 23, 2022
JustPersist is the easiest and safest way to do persistence on iOS with Core Data support out of the box.
JustPersist is the easiest and safest way to do persistence on iOS with Core Data support out of the box.

JustPersist JustPersist is the easiest and safest way to do persistence on iOS with Core Data support out of the box. It also allows you to migrate to

Mar 13, 2022
A powerful and elegant Core Data framework for Swift.
A powerful and elegant Core Data framework for Swift.

A powerful and elegant Core Data framework for Swift. Usage Beta version. New docs soon... Simple do that: let query = persistentContainer.viewContext

May 23, 2022
Unleashing the real power of Core Data with the elegance and safety of Swift
 Unleashing the real power of Core Data with the elegance and safety of Swift

Unleashing the real power of Core Data with the elegance and safety of Swift Dependency managers Contact Swift 5.4: iOS 11+ / macOS 10.13+ / watchOS 4

Jun 25, 2022
JSON to Core Data and back. Swift Core Data Sync.
JSON to Core Data and back. Swift Core Data Sync.

Notice: Sync was supported from it's creation back in 2014 until March 2021 Moving forward I won't be able to support this project since I'm no longer

Jun 8, 2022
A Swift framework that wraps CoreData, hides context complexity, and helps facilitate best practices.
A Swift framework that wraps CoreData, hides context complexity, and helps facilitate best practices.

Cadmium is a Core Data framework for Swift that enforces best practices and raises exceptions for common Core Data pitfalls exactly where you make the

May 17, 2022
A small set of utilities to make working with CoreData and Swift a bit easier.

SuperRecord =================== SUPPORTS SWIFT 2.0 from Version >= 1.4 ** SUPPORTS SWIFT 1.2 from Version <= 1.3 Both iOS and WatchOS A Swift CoreData

May 14, 2022
A Swift framework that wraps CoreData, hides context complexity, and helps facilitate best practices.
A Swift framework that wraps CoreData, hides context complexity, and helps facilitate best practices.

Cadmium is a Core Data framework for Swift that enforces best practices and raises exceptions for common Core Data pitfalls exactly where you make them.

May 17, 2022
A minimalistic, thread safe, non-boilerplate and super easy to use version of Active Record on Core Data.
A minimalistic, thread safe, non-boilerplate and super easy to use version of Active Record on Core Data.

Skopelos A minimalistic, thread-safe, non-boilerplate and super easy to use version of Active Record on Core Data. Simply all you need for doing Core

May 11, 2022
Domain Specific Language to safely build predicates and requests to fetch a CoreData store

SafeFetching This library offers a DSL (Domain Specific Language) to safely build predicates and requests to fetch a CoreData store. Also a wrapper ar

May 8, 2022
Quillow is an elegant book management app on the App Store that allows you to search, add and track the books you've consumed.

Quillow Quillow is an elegant book management app on the App Store that allows you to search, add and track the books you've consumed. Please use the

May 17, 2022
Select the right architecture and functional reactive programming framework

#boilerplate This repository demonstrates different architectures and usage of popular reactive programming frameworks. I decided to open-source coupl

Feb 11, 2022
SwiftUI - iOS notes App that integrates Core Data with SwiftUI App Life Cycle
SwiftUI - iOS notes App that integrates Core Data with SwiftUI App Life Cycle

Devote (Notes App) SwiftUI Masterclass project Integration between Core Data and SwiftUI App Life Cycle Custom Toggle style and checkbox Read, Update

Mar 16, 2022