hybrid xib + snapkit code

gistfile1.txt

// So you have inherited a monolithic complex xib file that extends over 50 constraints. 
// You change one constraint only to cause something else unrelated to break. 
// The TotalLossTimeDueToIB.com debt increases. 
// Xcode upgrades suggests adding more constraints - and slowly the view is becoming harder to juggle.
// It's a don't touch it unless it's broken and want to spend hours fixing it kind of smell. 
// Did I mention Xcode is breaking unsatisfiable constraints errors flooding the console?
//
// You wish you could make the break - and throw caution to the wind and use a DSL autolayout language like snapkit but it's
// too much risky to re-write completely. What if there was way in the middle road? 
// Instead of ditching the xibs and rolling out ui factory class - what if you could surgically re-wire some of the views to be handled by snapkit and slowly toss out the existing IB constraints. IF so - proceed with caution.
//
// Don't know snapkit? Checkout
// https://github.com/johndpope-karhoo/SnapKitExamples

// Instructions
// Step 1 - Add tags to your container views in IB  
// Not using container views? (You probably want to use these where ever possible to hold labels / images etc). 
// NB. Avoid using IBOutlets if you can to these uiview subclasses. 
// The code below will remove any xcode constraints imposed by IB on current view.
// Step 2. subclass the views in IB to your bespoke OptionsView instead of UIView


import Foundation
import SnapKit

let screenWidth = UIScreen.mainScreen().bounds.width

class SnapKitHelperView:UIView{
    
    var debugConstraints = false

    func getRandomColor() -> UIColor{
        let randomGreen:CGFloat = CGFloat(drand48())
        let randomBlue:CGFloat = CGFloat(drand48())
        return UIColor(red: 1, green: randomGreen, blue: randomBlue, alpha: 1.0)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()

        
        if(debugConstraints){
            for c in self.constraints{
                print("constraints:",c)
            }
            self.backgroundColor = self.getRandomColor();
        }
    }
    
    func labelByTag(tag:Int) -> UILabel{
        if let view = self.viewWithTag(tag) as? UILabel{
            return view;
        }else{
            print("FATAL missing label by tag ",tag)
            fatalError()
        }
        return UILabel()
    }
    func viewByTag(tag:Int) -> UIView{
        if let view = self.viewWithTag(tag){
            return view;
        }else{
            print("FATAL missing view by tag ",tag)
            fatalError()
        }
        return UIView()
    }
    func imageViewByTag(tag:Int) -> UIImageView{
        if let view = self.viewWithTag(tag) as? UIImageView{
            return view;
        }else{
            print("FATAL missing image by tag ",tag)
            fatalError()
        }
        return UIImageView()
    }
    
}







class OptionsView:SnapKitHelperView{
    
    private let kPadding: Float = 10.0
    
    private lazy var lineContainer: UIView = self.viewByTag(400)
    private lazy var cancelContainer: UIView = self.viewByTag(401)
    private lazy var messageContainer: UIView = self.viewByTag(402)
    private lazy var callContainer: UIView = self.viewByTag(403)
    
    var runOnce = false
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
         self.backgroundColor = UIColor.whiteColor();
        
        // REMOVE XCODE CONSTRAINTS ONCE
        if (!runOnce){
            runOnce = true
            self.removeConstraints(self.constraints)
        }
        
        self.snp_makeConstraints { (make) -> Void in
            make.width.equalTo(screenWidth)
            make.height.equalTo(107)
        }
        
        // Top Line
        lineContainer.snp_makeConstraints { (make) -> Void in
            make.top.equalTo(self)
        }
        
        // Cancel
        cancelContainer.snp_makeConstraints { (make) -> Void in
            make.left.equalTo(self).offset(25)
            make.top.equalTo(self).offset(10)
        }
        
        //Message
        callContainer.snp_makeConstraints { (make) -> Void in
            make.right.equalTo(self).offset(-25)
            make.top.equalTo(self).offset(10)
        }
        
        // Call Driver
        messageContainer.snp_makeConstraints { (make) -> Void in
            make.center.equalTo(self)
            make.top.equalTo(self).offset(10)
        }
        
        
        
    }
}

Example container with IB constraints - these smaller constraint logic for label /heights /widths etc can live another day.

Adding Tags eg. 400 = lineContainer

We want to use snapkit to orchestrate the container layout logic at a higher level.
Here we change the Options uiview to subclass OptionsView instead.
You will want to prefix views with SnapKit - eg. SnapOptionsView to provide clarity to people picking up code next / consider adding to readme if need be.

N.B - you can recurse into children subviews too if you wish to do so.
for subView in self.subviews{
subView.removeConstraints(subView.constraints)
}

You can use Visual Studio Code -> and change syntax to Jade to get better readability.
Add identifiers to constraints here > http://useyourloaf.com/blog/using-identifiers-to-debug-autolayout/

Probably obsolete with xcode 8 - but you can dig up these labels / constraints here

https://medium.com/ios-os-x-development/auto-layout-debugging-in-swift-93bcd21a4abf#.lrojezfle

http://useyourloaf.com/blog/auto-layout-and-alignment-rectangles/