SpacyRicochet · January 29, 2017 19:17 · Jan 29, 2017
diff --git a/Playgrounds.swift b/Playgrounds.swift
@@ -0,0 +1,96 @@
+import UIKit
+import PlaygroundSupport
+
+//: NSLayoutConstraint convenience methods
+public extension NSLayoutConstraint {
+
+    public static func pinning(attribute: NSLayoutAttribute, ofView firstView: UIView, toView secondView: UIView, multiplier: CGFloat = 1, offset: CGFloat = 0) -> NSLayoutConstraint {
+        return NSLayoutConstraint(item: firstView, attribute: attribute, relatedBy: .equal, toItem: secondView, attribute: attribute, multiplier: multiplier, constant: offset)
+    }
+
+    public static func pinning(attributes: [NSLayoutAttribute], ofView firstView: UIView, toView secondView: UIView, multiplier: CGFloat = 1, offset: CGFloat = 0) -> [NSLayoutConstraint] {
+        return attributes.map { return NSLayoutConstraint(item: firstView, attribute: $0, relatedBy: .equal, toItem: secondView, attribute: $0, multiplier: multiplier, constant: offset) }
+    }
+
+    public static func pinningCenterOfView(_ firstView: UIView, toView secondView: UIView, offset: (CGPoint) = .zero) -> [NSLayoutConstraint] {
+        let xConstraint = pinning(attribute: .centerX, ofView: firstView, toView: secondView, offset: offset.x)
+        let yConstraint = pinning(attribute: .centerY, ofView: firstView, toView: secondView, offset: offset.y)
+        return [xConstraint, yConstraint]
+    }
+
+    public static func pinningAttribute(attribute: NSLayoutAttribute, ofView view: UIView, toConstant constant: CGFloat) -> NSLayoutConstraint {
+        return NSLayoutConstraint(item: view, attribute: attribute, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: constant)
+    }
+
+    public static func pinningSizeOfView(view: UIView, to size:CGSize) -> [NSLayoutConstraint] {
+        let widthConstraint = NSLayoutConstraint.pinningAttribute(attribute: .width, ofView: view, toConstant: size.width)
+        let heightConstraint = NSLayoutConstraint.pinningAttribute(attribute: .height, ofView: view, toConstant: size.height)
+        return [widthConstraint, heightConstraint]
+    }
+
+}
+
+//: UIView convenience methods
+extension UIView {
+    @discardableResult public func pinSubviewToCenter(_ subview: UIView, offset: CGPoint = .zero) -> (centerX: NSLayoutConstraint, centerY: NSLayoutConstraint)? {
+        guard subview.superview == self else { return nil }
+        let constraints = NSLayoutConstraint.pinningCenterOfView(subview, toView: self)
+        self.addConstraints(constraints)
+        return (centerX: constraints[0], centerY: constraints[1])
+    }
+
+    @discardableResult public func pinSize(_ size: CGSize) -> (width: NSLayoutConstraint, height: NSLayoutConstraint) {
+        let constraints = NSLayoutConstraint.pinningSizeOfView(view: self, to: size)
+        self.addConstraints(constraints)
+        return (width: constraints[0], height: constraints[1])
+    }
+
+    @discardableResult public func pinSubviewToBounds(_ subview: UIView, offset: CGFloat = 0) -> (top: NSLayoutConstraint, left: NSLayoutConstraint, bottom: NSLayoutConstraint, right: NSLayoutConstraint)? {
+        return pinSubviewToBounds(subview, ofView: self, offset: offset)
+    }
+
+    @discardableResult public func pinSubviewToBounds(_ subview: UIView, ofView view: UIView, offset: CGFloat = 0) -> (top: NSLayoutConstraint, left: NSLayoutConstraint, bottom: NSLayoutConstraint, right: NSLayoutConstraint)? {
+        guard subview.superview == self, (view == self || view.superview == self) else { return nil }
+
+        let constraints = NSLayoutConstraint.pinning(attributes: [.top, .left, .bottom, .right], ofView: subview, toView: view)
+        self.addConstraints(constraints)
+        return (top: constraints[0], left: constraints[1], bottom: constraints[2], right: constraints[3])
+    }
+
+    @discardableResult public func pinAttribute(_ subviewAttribute: NSLayoutAttribute, ofSubview subview: UIView, toAttribute attribute: NSLayoutAttribute, ofView view: UIView, multiplier: CGFloat = 1, offset: CGFloat = 0) -> NSLayoutConstraint? {
+        guard subview.superview == self, (view == self || view.superview == self) else { return nil }
+
+        let constraint = NSLayoutConstraint(item: subview, attribute: subviewAttribute, relatedBy: .equal, toItem: view, attribute: attribute, multiplier: multiplier, constant: offset)
+        self.addConstraint(constraint)
+        return constraint
+    }
+}
+
+//: Test code
+
+let view = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
+view.backgroundColor = UIColor.black
+
+let redView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
+redView.translatesAutoresizingMaskIntoConstraints = false
+redView.backgroundColor = UIColor.red
+redView.pinSize(CGSize(width: 200, height: 200))
+view.addSubview(redView)
+
+let blueView = UIView(frame: .zero)
+blueView.translatesAutoresizingMaskIntoConstraints = false
+blueView.backgroundColor = UIColor.blue
+blueView.pinSize(CGSize(width: 100, height: 100))
+view.addSubview(blueView)
+
+let greenView = UIView(frame: .zero)
+greenView.translatesAutoresizingMaskIntoConstraints = false
+greenView.backgroundColor = UIColor.green
+greenView.pinSize(CGSize(width: 75, height: 75))
+view.addSubview(greenView)
+
+view.pinSubviewToCenter(blueView)
+view.pinAttribute(.leading, ofSubview: greenView, toAttribute: .trailing, ofView: blueView)
+view.pinAttribute(.bottom, ofSubview: greenView, toAttribute: .bottom, ofView: view, offset: -25)
+
+PlaygroundPage.current.liveView = view