當點擊背景的時候出發事件，或者跳轉界面或者產生其他的響應

-(void)viewDidLoad

{

   UIImageView * imageView  = [UIImageView alloc]initWithFrame:CGRectmake

(20,20,200,100)]  ;

  imageView.image = [UIImage imageName:@"aa.png"];

 imageView.userInterationEnable = YES;

  //主要的事應用這個類的方法

  UITapGesturRecognizer * TapGesturRecognizer = [UITapGestureRecognizer alloc]

initWithTarget:self         action:@selecter(tapGestureRecognizer);

[imageView addGestureRecognizer:TapGesturRecognizer ];

[self.view addSubview:imageView];

}

//點擊圖片時，釋放掉textfile的鍵盤

-(void)tapGestureRecognizer

{

   [self.textfile resignFirstRsponder];