长按手势（UILongPressGestureRecognizer）简介

长按手势一定需要和UIGestureRecognizer类的state属性进行配合使用，即通过不同状态state下，实现不同的功能。UIGestureRecognizer类的state属性中，常见的有：

• UIGestureRecognizerStateBegan：开始手势事件
• UIGestureRecognizerStateEnded：结束手势事件
• UIGestureRecognizerStateChanged：手势位置发生变化
• UIGestureRecognizerStateFailed：无法识别的手势

//长按手势
 UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
 [self.imageView addGestureRecognizer:longPressGesture];

//响应事件
-(void) longPress: (UILongPressGestureRecognizer *) gesture {
 if (gesture.state == UIGestureRecognizerStateBegan) {
 NSLog(@"长按开始");
 self.longPressLable.text = @"长按开始";
 }else if (gesture.state == UIGestureRecognizerStateEnded){
 NSLog(@"长按结束");
 self.longPressLable.text = @"长按结束";
 }
 else {
 NSLog(@"长按中");
 self.longPressLable.text = @"长按中";
 }
}