JSONLayout

iOS Auto Layout with JSON and VFL

How to define layout in JSON:

{
    "views": {
        "V1": {
            "type": "UIView",
            "children": {
                "L1": {
                    "type": "UILabel"
                }
            }
        },
        "V2": {
            "type": "UIView",
            "children": {
                "L2": {
                    "type": "UILabel"
                }
            }
        }
    },
    "metrics": {
        "M1": 20.0,
        "M2": 100.0,
    },
    "constraints": {
        "C1": "H:|-M2-[V1(220)]",
        "C2": "H:|-M2-[V2(130)]",
        "C3": "V:|-M2-[V1(120)]-50-[V2(==V1)]",
        "C4": "H:|-M1-[L1(30)]",
        "C5": "H:|-M1-[L2(30)]",
        "C6": "V:|-M1-[L1(30)]",
        "C7": "V:|-M1-[L2(30)]"
    }
}

Gotcha: if the view class in not a part of UIKit, specify its full name including module, i.e. MyApp.MyView.

How to use it in code:

import JSONLayout

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        try? Layout(name: "layout").inflate(in: view)        
        view.findViewByID("V1")?.backgroundColor = UIColor.blue
        view.findViewByID("V2")?.backgroundColor = UIColor.yellow
        view.findViewByID("L1")?.backgroundColor = UIColor.green
        view.findViewByID("L2")?.backgroundColor = UIColor.red
    }

}

For further customization of views and constraints, implement some or all lambdas in configure clause as follows:

try? Layout(name: "layout").configure {
    // customize format options
    $0.formatOptions = { (id) -> NSLayoutConstraint.FormatOptions in [] }
    // provide view yourself (if the class does not have default initializer) or fall back to the default implementation
    $0.viewOfType = { (type, id) -> UIView? in return Layout.view(of: type) }
    // configure a newly created view
    $0.didCreateView = { (view, id) -> Void in return }
}
.inflate(in: view)

Carthage setup:

github "maxvol/JSONLayout" ~> 0.0.8