Swift - 回调机制

1.类似于TableViewCell中的didselected方法的直接回调

2.Closure闭包回调

import UIKitclass ViewController: UIViewController {    var str:String!    overridefunc viewDidLoad() {        super.viewDidLoad()        let vc2 = ViewController2()//        self.presentViewController(vc2, animated: true, completion: nil)        vc2.sayHello { (callback) -> Voidin            self.str = callback            print("\(callback)")        }    }}import UIKitclass ViewController2: UIViewController {    overridefunc viewDidLoad() {        var v = UIView(frame: UIScreen.mainScreen().bounds)        print("this is vc2")    }    func sayHello (completionHandler:(callback:String) -> Void) {        let str = "Hello234trgsdfa"        completionHandler(callback:str)    }}

3.delegate代理回调

https://github.com/shileseal/SLSwiftDelegateDemo