当点击背景的时候出发事件，或者跳转界面或者产生其他的响应

-(void)viewDidLoad

{

   UIImageView * imageView  = [UIImageView alloc]initWithFrame:CGRectmake

(20,20,200,100)]  ;

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

 imageView.userInterationEnable = YES;

  //主要的事应用这个类的方法

  UITapGesturRecognizer * TapGesturRecognizer = [UITapGestureRecognizer alloc]

initWithTarget:self         action:@selecter(tapGestureRecognizer); 

[imageView addGestureRecognizer:TapGesturRecognizer ];

[self.view addSubview:imageView]; 

}

//点击图片时，释放掉textfile的键盘

-(void)tapGestureRecognizer

{

   [self.textfile resignFirstRsponder];

}