关于选择者的问题 [英] question about selectors

问题描述

我有以下内容：

  UITapGestureRecognizer *tapGesture;
    SEL sel = @selector(profilePop:withUser:) withObject:tapGesture withObject:message.creator;
    tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:sel];

我想让它能够致电：

- (void)profilePop:(UITapGestureRecognizer *)recognizer withUser:(Login *)user
{
    //some code here
}

但为什么不这样做？

推荐答案

选择器只知道它的名称和任何参数名称，而不是它的参数。

A selector only knows about its name and any parameter names, not its arguments.

UIGestureRecognizer 只接受接受其类型为零或一个参数的操作。

UIGestureRecognizer only accepts actions which take in either zero or one argument of its type.

为了做你想做的事，你需要写一个包装器方法来将 Login 实例传递给 profilePop：withUser：。

In order to do what you want, you'll need to write a wrapper method to pass off a Login instance to profilePop:withUser:.

所以，你写的是这样的：

So, you'd write something like this:

UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(profilePopWrapper:)];
[[self view] addGestureRecognizer:tapGesture];
[tapGesture release];


//....

- (void) profilePopWrapper:(UIGestureRecognizer *) gr {
    Login *someUser = ...;
    [self profilePop:gr withUser:someUser];
}

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