UIView和UIWindow的使用

1.创建窗口:

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        // 1.创建窗口
        window = UIWindow(frame: UIScreen.mainScreen().bounds)
        window?.backgroundColor = UIColor.whiteColor()
        window?.makeKeyAndVisible()
        
        // 2.设置根控制器 不需要导入控制器即可
        var root = ViewController()
        window?.rootViewController = root
        
        return true
    }

　　

2.创建视图

 override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = UIColor .greenColor()
        //创建view
        var myView = UIView(frame: CGRectMake(20,100,50,50))
        myView.backgroundColor = UIColor.redColor()
        view .addSubview(myView)
    }