UIImageView并不像UIButton那样点击鼠标就可以关联点击事件，也不像Android里有onClickListener，这个时候就需要借助UITapGestureRecognizer类，从类名上就可以看出，这个类就是用于处理tap(单击)事件的。

创建两个UIImageView对象,imageView1和imageView2

    [imageView1 setUserInteractionEnabled:YES];
    [imageView2 setUserInteractionEnabled:YES];
    [imageView1 addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickCategory:)]];
    [imageView2 addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickCategory:)]];

经测试，多个UIImageView不能共用一个UITapGestureRecognizer对象，之前调用的会没效果。
根据点击的view判断来自谁的点击

-(void)clickCategory:(UITapGestureRecognizer *)gestureRecognizer
{
    NSLog(@"click");
    NSLog(@"%hhd",[gestureRecognizer isMemberOfClass:[UITapGestureRecognizer class]]);
    
    UIView *viewClicked=[gestureRecognizer view];
    if (viewClicked==imageView1) {
        NSLog(@"imageView1");
    }else if(viewClicked==imageView2)
    {
        NSLog(@"imageView2");
    }
  
}

iOS:UIImageView添加点击事件