FlightLayout

Introduction

FlightLayout is a light weight, and easy to learn layout framework as an extension of the UIView. Functionally, it lives somewhere in between the manual process of laying out views from the old days, and the flexibility of Autolayout's dynamic constraint approach.

Some use cases for this framework include the ability to animate views with core animation. Without the overhead of Autolayout's constraints system, we are free to apply animations without the hassle of disabling constraints to perform parametric animations to a layer's properties.

Demo

Since the scope of the documentation is limited to a handful of examples, once you have finished with the reading the documentation below, feel free to clone the project and run the demo app with the project. The demo app provides the ability to pick different options in the method call, once selected, the app will align a demo view on the screen to it's final frame, and provide a code example to reflect it.

An example of how the view controller is laid out in the demo app is can be found here

Installation

• Installation Documentation

Basic Use

The UIView Extension which contains the align method, when called by a view, the calling view will set it's own frame relatively as specified by the parameters in the method call . The method constraints 6 optional parameters with assigned defaults, thus creating very powerful and flexible method signature with lots of possibilities. See below for an in-depth examples below for definitions of each parameter.

There are two enumerators defined for horizontal and vertical alignment. These are the magic options that allow you to align the calling view relative to another frame.

func align(toFrame frame    : CGRect? = nil,
           withSize size    : CGSize? = nil,        
           horizontal       : HorizontalAlign,  
           vertical         : VerticalAlign,
           horizontalOffset : CGFloat = 0.0,
           verticalOffset   : CGFloat = 0.0)

When performing animations, there often comes a need to calculate the frame to perform an animation. The following method returns a pre-calculate the frame based on the method parameters included, without actually setting it on the calling view. The align method actually this to calculate it's final value.

func rectAligned(toFrame frame    : CGRect  = CGRectZero,
                 withSize size    : CGSize? = nil,
                 horizontal       : HorizontalAlign,
                 vertical         : VerticalAlign,
                 horizontalOffset : CGFloat = 0.0,
                 verticalOffset   : CGFloat = 0.0) -> CGRect

Horizontal Alignment

The following horizontal options align the calling view on the horizontal plane, with illustrations below

public enum HorizontalAlign {
    case left           // Align horizontally to the Left
    case leftEdge       // Align horizontally to the Left Edge
    case center         // Align center.y horizontally
    case rightEdge      // Align horizontally to the Right Edge
    case right          // Align horizontally to the Right
}

Vertical Alignment

The vertical options align the calling view on the vertical plane, with illustrations below

public enum VerticalAlign {
    case above          // Align vertically Above
    case top            // Align vertically to the top
    case center         // Align center.y vertically
    case base           // Align vertically to the base
    case below          // Align vertically Below
}

Example 1

In the following example, first we add the a new view named bigView as a subview, and say you want to align it dead center relative to the superview's bounds. It's as calling align against the view with the following method. This call with align the big bigView against the view's bounds that it was added to, with a horizontal, and vertical, alignment of .center.

view.addSubview(bigView)

bigView.align(toFrame   : view.bounds,     
   			     withSize   : CGSize(width : 140.0, height : 140.0),        
             horizontal : .center,  
             vertical   : .center)

Note: In the case that the calculated frame is the same as the calling views frame, it will not actually set the frame on the caller, it will just exit. This helps avoid glitches during animations, i.e setting the frame on the view that is currently animating, will flicker the view to it's final position.

Example 2

The call in Example 1 can also be expressed by omitting toFrame parameter. In the absence of the toFrame parameter from the method call, the framework automatically assumes that you are intending to align the calling view against the it's superview's bounds.

view.addSubview(bigView)

bigView.align(withSize   : CGSize(width : 140.0, height : 140.0),        
              horizontal : .center,  
              vertical   : .center)

Example 3

What if we implemented a sizeToFit() method on our calling view. In the absence of the withSize parameter from the method call, the framework automatically assumes that you are intending to use the current size of the calling view.

view.addSubview(bigView)

bigView.sizeToFit()
bigView.align(horizontal : .center,  
              vertical   : .center)

Example 4

The above example, can also be expressed by omitting horizontal and vertical parameters. In the absence of the horizontal and vertical parameters from the method call, the framework automatically assumes that you are intending to align the calling view's to the center horizontally, and vertically, by defaulting to .Center.

view.addSubview(bigView)

bigView.sizeToFit()
bigView.align()

Horizontal & Vertical Offset

The horizontalOffset and verticalOffset parameters adjust the calling view's final frame on the horizontal and vertical alignment parameters.

Lets assume we want to center the view and adjust it 20px right, and 20px upward. We can do this by including the horizontalOffset and verticalOffset and update the offset as follows.

view.addSubview(bigView)

bigView.sizeToFit()
bigView.align(horizontal       : .center,  
              vertical         : .center,
              horizontalOffset : 20.0,
              verticalOffset   : -20.0)

License

 Copyright (c) 2016 Anton Doudarev  

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