ios - UIGestureRecognizer 是否知道调用它的对象是什么？

Question

我有一个 UIGestureRecognizer，我想在两个不同的 UIView 上工作，它们都在 UiViewController 的同一视图层次结构中。UIGestureRecognizer 的动作在每一个上都差不多，所以我希望调用相同的函数（很明显），我会在运行时告诉我正在处理哪些 UIView。但是怎么做？我看不到 UIGestureRecognizer 正在携带对象信息。我是否错过了文档中的这一行，或者gestureRecognizer不知道它附加到哪个对象上被调用？似乎语言的重点在于它会知道。

或者，也许我误解了课程的意图，我不应该：

UITapGestureRecognizer *dblTap = 
[[UITapGestureRecognizer alloc] initWithTarget: self 
                                        action: @selector(handleDblTap:)];   
[viewA addGestureRecognizer: dblTap]; 
[viewB addGestureRecognizer: dblTap];

然后期望能够：

-(void)handleDblTap: (UIGestureRecognizer *)gestureRecognizer
{
     if (viewA)...

如果实际上 UIGestureRecognizer 不支持同时附加到多个对象，那么，如果你知道它为什么不支持这个，你能教育我吗？谢谢您的帮助。

Answer 1

The standard is one view per recognizer. But you can still efficiently use one handler method.

You would instantiate the recognizers like so:

UITapGestureRecognizer *dblTapViewA = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDblTap:)];   
[viewA addGestureRecognizer: dblTapViewA]; 

UITapGestureRecognizer *dblTapViewB = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDblTap:)];
[viewB addGestureRecognizer: dblTapViewB];

Then your handler method could look something like:

-(void)handleDblTap:(UITapGestureRecognizer *)tapRec{
    if (tapRec.view == viewA){
        // double tap view a
    } else if (tapRec.view == viewB) {
        // double tap view b
    }
}

Answer 2

您可以分配一个标签来查看，然后简单地比较该标签并执行操作。

UITapGestureRecognizer *dblTap = 
[[UITapGestureRecognizer alloc] initWithTarget: self 
                                    action: @selector(handleDblTap:)];   
[view addGestureRecognizer: dblTap];
view.tag = 2000; // set any integer 

打电话的时候

-(void)handleDblTap:(UITapGestureRecognizer *)tapRec{
    if (tapRec.view.tag == 2000){
      // double tap view with tag
    } 
}

Answer 3

UITapGestureRecognizer *dblTapA = 
[[UITapGestureRecognizer alloc] initWithTarget: self 
                                    action: @selector(handleDblTap:)];   
[viewA addGestureRecognizer: dblTapA]; 

UITapGestureRecognizer *dblTapB = 
[[UITapGestureRecognizer alloc] initWithTarget: self 
                                    action: @selector(handleDblTap:)];   
[viewA addGestureRecognizer: dblTapB];