swift篇第四期：闭包、UI基础、Protocol

首先来讲下闭包吧，其实闭包跟之前C中的block回调函数类似，但这里只研究了基础的使用，我在下面的两个VC中利用闭包做了通讯传值，也算是比较常用的方法吧，回头有时间我再研究下在项目中的其它应用

 let sayHello = {    println("nihao")}sayHello()//定义一个闭包函数，与常规方法不同的是后面有个关键字in哦let add = { (a: Int, b: Int) -> Int in    return a + b}//调用的时候其实跟调用方法一样哦println(add(1, 2))//下面就是一个简单的例子，来找出数组中大于等于value的值，如果有，返回Yesvar array = [20, 9, 100, 34, 89, 39]func hasClosureMatch(array: [Int], value: Int, closureValue: (num:Int, value:Int)-> Bool)-> Bool {    for item in array {        if (closureValue(num: item, value: value)) {            return true        }    }    return false}//Closure 闭包var v1 = hasClosureMatch(array, 40) { (num, value) -> Bool in    return num >= value}println(v1)

然后是UI基础的代码，可以直接创建单一控制器的工程，主要是为了熟悉一下代码

这里我们可以先把storyboard关掉，直接改动appdelegate里面的方法

UI这里面就没有太多要讲的，主要是多查查相关的API，然后慢慢积累咯

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {        // Override point for customization after application launch.        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)        self.window!.backgroundColor = UIColor.whiteColor()        self.window!.makeKeyAndVisible()                //从语法上，我觉得跟O-C真的很不一样，但是道理是通的，如果你的O-C语言还算熟练，我想上手swift语言也是很轻松的        let rootViewController = RootViewController()        let navigationController = UINavigationController(rootViewController: rootViewController)        navigationController.tabBarItem = UITabBarItem(title: "第一页", p_w_picpath: nil, tag: 1)                let secondViewController = SecondViewController()        let secondNavigationController = UINavigationController(rootViewController: secondViewController)        secondNavigationController.tabBarItem = UITabBarItem(title: "第二页", p_w_picpath: nil, tag: 2)                let array = [navigationController, secondNavigationController];        let tabBarController = UITabBarController()        tabBarController.viewControllers = array                self.window!.rootViewController = tabBarController                return true    }

接下来我们创建两个VC的类，Swift里面并没有所谓的指定类创建，而是在swift文件里，我们可以创建好多好多的类，当然了，为了更好的区分，我就单独创建类吧

这样我们在两个类里面单独创建一些基础的控件，然后再写一个协议来运用起来

主要还算来熟悉一下相关的语法

在下面的代码中也用到了Protocol以及Closure，方便小伙伴们上手哦

 class RootViewController: UIViewController, ViewChangeDelegate {    var clickCount:Int = 0;    var myLabel:UILabel?        override func viewDidLoad() {        super.viewDidLoad()                self.title = "炉石传说"                let nextItem = UIBarButtonItem(title: "下一页", style: .Plain, target: self, action: "nextPage:")        self.navigationItem.rightBarButtonItem = nextItem                myLabel = UILabel(frame: CGRect(x: 0, y: 100, width: 320, height: 44))        myLabel!.text = "小华，你好啊"        myLabel!.backgroundColor = UIColor.redColor()        self.view.addSubview(myLabel!)                var myButton = UIButton(frame: CGRect(x: 100, y: 200, width: 100, height: 44))        myButton.backgroundColor = UIColor.blueColor()        myButton.setTitle("点击", forState: .Normal)        myButton.addTarget(self, action: "clickMe:", forControlEvents: .TouchUpInside)        self.view.addSubview(myButton)    }        func clickMe(sender:UIButton) {        clickCount += 1;        println("click\(clickCount)")        myLabel!.text = "你猜我点了几次呢，\(clickCount)"    }        func nextPage(sender:UIButton) {        let secondViewController = SecondViewController()        secondViewController.viewChangeDelegate = self        secondViewController.changeTextForClosure("1", num: 1) { (value, num) -> Void in            myLabel?.text = value        }        self.navigationController?.pushViewController(secondViewController, animated: true)    }        func changeTitleToString(controller:UIViewController, value:String) {        myLabel!.text = value    }

 import Foundationimport UIKitclass SecondViewController: UIViewController {    var viewChangeDelegate:ViewChangeDelegate?    var closure = { (value:String, num:Int) -> Void in            }        override func viewDidLoad() {        super.viewDidLoad()                self.title = "第二页"        self.view.backgroundColor = UIColor.grayColor()                var button = UIButton.buttonWithType(.System) as! UIButton        button.frame = CGRect(x: 100, y: 100, width: 100, height: 40)        button.setTitle("返回上一页", forState: .Normal)        button.addTarget(self, action: "back:", forControlEvents: .TouchUpInside)        self.view.addSubview(button)                var buttonChange = UIButton.buttonWithType(.System) as! UIButton        buttonChange.frame = CGRect(x: 100, y: 200, width: 100, height: 40)        buttonChange.setTitle("改变首页label值", forState: .Normal)        buttonChange.addTarget(self, action: "change:", forControlEvents: .TouchUpInside)        self.view.addSubview(buttonChange)    }        func changeTextForClosure(value:String, num:Int, closureValue:(value:String, num:Int) -> Void) {        self.closure = closureValue    }        func change(sender:UIButton) {        if ((viewChangeDelegate) != nil) {            viewChangeDelegate?.changeTitleToString(self, value: "我变变变")        }        self.closure("你好", 1)    }        func back(sender:UIButton) {        self.navigationController?.popToRootViewControllerAnimated(true)    }}protocol ViewChangeDelegate : NSObjectProtocol {    func changeTitleToString(controller:UIViewController, value:String)}

好啦，就先写这么多吧