Auto Closure

gistfile1.txt

import UIKit
import XCPlayground

// Enable simulator to view results in playground

extension UIView {
    class func animate(duration : NSTimeInterval, @autoclosure _ animations : () -> Void) {
        UIView.beginAnimations(nil, context: nil)
        UIView.setAnimationDuration(duration)
        animations()
        UIView.commitAnimations()
    }
}

// This does not work
//extension UIView {
//    class func animate(duration : NSTimeInterval, @autoclosure _ animations : () -> Void) {
//        // This does not work: Invalid use of non-escaping function in escaping context
//        // Cannot invoke with argument list of NSTimeInterval, @autoclosure () -> Void
//        UIView.animateWithDuration(duration, animations: animations) // error
//    }
//}

let view = UIView(frame:CGRectMake(0, 0, 200, 180))
view.backgroundColor = .redColor()
XCPShowView("View", view)

UIView.animate(2.0, view.backgroundColor = .blueColor())