POC of syntax improvement to manual frame layout in Swift.

frame-layout.swift

//: Playground - noun: a place where people can play

import UIKit
import PlaygroundSupport


struct Frame {
    let x: CGFloat
    let y: CGFloat
    let width: CGFloat
    let height: CGFloat
    
    // MARK: Margins
    
    func with(margins: (top: CGFloat, left: CGFloat, bottom: CGFloat, right: CGFloat)) -> Frame {
        return Frame(x: x + margins.left,
                     y: y + margins.top,
                     width: width - margins.left - margins.right,
                     height: height - margins.top - margins.bottom)
    }
    
    // MARK: Distribution
    
    struct EqualDistribution {
        struct Horizontal {
            let frame: Frame
            
            func take(index: Int, of count: Int) -> Frame {
                let distributedSize = frame.width / CGFloat(count)
                return Frame(x: frame.x + CGFloat(index) * distributedSize,
                             y: frame.y,
                             width: distributedSize,
                             height: frame.height)
            }
        }
        
        struct Vertical {
            let frame: Frame
            
            func take(index: Int, of count: Int) -> Frame {
                let distributedSize = frame.height / CGFloat(count)
                return Frame(x: frame.x,
                             y: frame.y + CGFloat(index) * distributedSize,
                             width: frame.width,
                             height: distributedSize)
            }
        }
    }
    
    var distributeHorizontally: EqualDistribution.Horizontal {
        return EqualDistribution.Horizontal(frame: self)
    }
    
    var distributeVertically: EqualDistribution.Vertical {
        return EqualDistribution.Vertical(frame: self)
    }
    
    // MARK: Slicing
    
    struct Slice {
        let frame: Frame
        let size: CGSize
        
        func fromTopRightCorner(topMargin: CGFloat, rightMargin: CGFloat) -> Frame {
            return Frame(x: frame.x + frame.width - rightMargin - size.width,
                         y: topMargin,
                         width: size.width,
                         height: size.height)
        }
        
        /// TODO: fromTopLeftCorner ...
        /// TODO: fromBottomRightCorner ...
        
        func fromBottomLeftCorner(bottomMargin: CGFloat, leftMargin: CGFloat) -> Frame {
            return Frame(x: frame.x + leftMargin,
                         y: frame.y + frame.height - bottomMargin - size.height,
                         width: size.width,
                         height: size.height)
        }
    }
    
    func slicedFrame(ofSize size: CGSize) -> Slice {
        return Slice(frame: self, size: size)
    }
    
    // MARK: Convenience
    
    var rect: CGRect {
        return CGRect(x: x, y: y, width: width, height: height)
    }
}



// MARK: Calculating layout

let containerFrame = Frame(x: 0, y: 0, width: 300, height: 300)
let redFrame = containerFrame
    .distributeHorizontally.take(index: 0, of: 2)
    .distributeVertically.take(index: 0, of: 2)
let blueFrame = containerFrame
    .distributeHorizontally.take(index: 1, of: 2)
    .distributeVertically.take(index: 1, of: 2)
    .with(margins: (top: 10, left: 10, bottom: 10, right: 10))
let yellowFrame = blueFrame.with(margins: (top: 10, left: 10, bottom: 10, right: 10))
let purpleFrame = containerFrame.slicedFrame(ofSize: CGSize(width: 90, height: 90))
                                .fromBottomLeftCorner(bottomMargin: 10, leftMargin: 10)


// MARK: Drawing

let view = UIView(frame: containerFrame.rect)
view.backgroundColor = .white

let redView = UIView(frame: redFrame.rect)
redView.backgroundColor = .red
view.addSubview(redView)

let blueView = UIView(frame: blueFrame.rect)
blueView.backgroundColor = .blue
view.addSubview(blueView)

let yellowView = UIView(frame: yellowFrame.rect)
yellowView.backgroundColor = .yellow
view.addSubview(yellowView)

let purpleView = UIView(frame: purpleFrame.rect)
purpleView.backgroundColor = .purple
view.addSubview(purpleView)

PlaygroundPage.current.liveView = view

Improved API idea:

Initialization

let containerFrame = Frame(width: 300, height: 300)

Grid distribution (rows & cols)

// "Divide frame ... into 2x2 grid and take (0, 0) frame"
let redFrame = containerFrame
    		   	.distributeTo(columns: 2).take(0)
    			.distributeTo(rows: 2).take(0)

// "Divide frame ... into 2x2 grid and take (1, 1) frame"
let blueFrame = containerFrame
			    .distributeTo(columns: 2).take(1)
			    .distributeTo(rows: 2).take(1)

Margins

// "Create frame by adding 10-points margin for each edge of blueFrame"
let yellowFrame = blueFrame.inset(top: 10, left: 10, bottom: 10, right: 10)

Relative Positioning

// "Put new frame of size ... below yellowFrame, and align it horizontally, then add y-offset
let anotherFrame = Frame(width: 90, height: 90)
					.putBelow(frame: yellowFrame)
					.alignHorizontally(.center)
					.offset(y: 10)