class ViewController: UIViewController {    override func viewDidLoad() {        super.viewDidLoad()                // 1. 自定义UIbutton类型为Custom        var btn : UIButton = UIButton.buttonWithType(UIButtonType.Custom) as UIButton                // 2. 设置UIButton的尺寸        btn.frame = CGRectMake(100, 50, 100, 30);                // 3. 设置普通状态下的button的字        btn.setTitle("swiftButton", forState: UIControlState.Normal)                // 4. 设置普通状态下的buton字的颜色        btn.setTitleColor(UIColor.redColor(), forState: UIControlState.Normal)                // 5. 设置高亮状态下的button的字的        btn.setTitle("HightLight", forState: UIControlState.Highlighted)                // 6. 设置高亮状态下的button的字的颜色        btn.setTitleColor(UIColor.blueColor(), forState: UIControlState.Highlighted)                // 7. 加载图片  ! 为可选类型,说明返回的图片一定是存在的不存在将崩溃        var btnImageN: UIImage = UIImage(named: "1")!        var btnImageHL: UIImage = UIImage(named: "2")!                // 8. 设置button的图片        //btn.setImage(btnImageN, forState: UIControlState.Normal)                // 9. 设置button的图片        //btn.setImage(btnImageHL, forState: UIControlState.Normal)                // 10. 设置普通状态下button的背景图片        btn.setBackgroundImage(btnImageN, forState: UIControlState.Normal)                // 11. 设置高亮状态下button的背景图片        btn.setBackgroundImage(btnImageHL, forState: UIControlState.Highlighted)                // 12. 设置UIButton的触发事件        btn.addTarget(self, action: "btnClick:", forControlEvents: UIControlEvents.TouchUpInside)                self.view.addSubview(btn)            }    func btnClick(btn:UIButton!)    {        println("btnClick")    }}