swift第四天学习

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ViewController.swift

import UIKit
//创建的入口和写UI时的入口是一样的，只不过将语言设置成swift
//遵守协议
class ViewController: UIViewController,SecondViewControllerDelegate {

override func viewDidLoad() {    super.viewDidLoad()    let button : UIButton = UIButton(type: UIButtonType.System)    button.frame = CGRectMake(100, 200, 50, 50)    button.backgroundColor = UIColor.magentaColor()    button.setTitle("点击", forState: UIControlState.Normal)    button.addTarget(self, action: "action", forControlEvents: UIControlEvents.TouchUpInside)    self.view.addSubview(button)}func action(){let secondVC = SecondViewController()    secondVC.delegate = self    secondVC.sendMessageBlock = {        (a : Int) in        print("block传过来的值\(a)")    }    self.presentViewController(secondVC, animated: true, completion: nil)}func getNumber(number: Int) {    print(number)}

}

SecondViewController.swift

import UIKit
//定义一个不是必须实现的协议（必须有 @objc 和 optional ）
@objc protocol SecondViewControllerDelegate {
optional func getNumber(number : Int)
}
//类型命名
typealias block = ((Int)->Void)

class SecondViewController: UIViewController {
//定义一个delegate，类型为SecondViewControllerDelegate
var delegate : SecondViewControllerDelegate?
//定义一个block属性
var sendMessageBlock : block! = nil
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor.cyanColor()
//初始化一个Button
let button : UIButton = UIButton(type:UIButtonType.System)
button.frame = CGRectMake(100, 200, 50, 50)
button.backgroundColor = UIColor.redColor()
button.setTitle(“点击”, forState: UIControlState.Normal)
button.addTarget(self, action: “action”, forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(button)
}
func action(){
//判断？修饰的是否有值
if let a = self.delegate {
print(“111(a)”)
a.getNumber!(1)
}
self.sendMessageBlock(2)
self.dismissViewControllerAnimated(true, completion: nil)
}
}