将参数传递给addTarget：action：forControlEvents [英] Passing parameters to addTarget:action:forControlEvents

问题描述

我使用addTarget：action：forControlEvents，如下所示：

  [newsButton addTarget：self 
 action：@selector（switchToNewsDetails）
 forControlEvents：UIControlEventTouchUpInside]; 
 

，我想传递参数给我的选择器switchToNewsDetails。
我成功的唯一办法是通过写（id）发送者：

  action：@selector（switchToNewsDetails：）

但我试图传递变量，如整数值。以这种方式写入不起作用：

  int i = 0; 
 [newsButton addTarget：self 
 action：@selector（switchToNewsDetails：i）
 forControlEvents：UIControlEventTouchUpInside]; 
 

这种写法无效：

  int i = 0; 
 [newsButton addTarget：self 
 action：@selector（switchToNewsDetails：i :) 
 forControlEvents：UIControlEventTouchUpInside]; 
 

任何帮助将不胜感激：）

解决方案

  action：@selector（switchToNewsDetails :) 
   
 
此处不传递参数到 switchToNewsDetails：方法。你只需创建一个选择器，使按钮能够调用它当某些行动发生时（在你的情况下触摸）。控件可以使用3种类型的选择器来响应动作，它们都具有其参数的预定义含义：
 
 
 
 
  action：@selector（switchToNewsDetails）
  
 / li> 
 
 
有一个指示发送消息的控件的参数
 选择器（switchToNewsDetails :) 
  
 
 
 
 
有两个参数指示发送消息和事件的控件触发消息：
 操作：@selector（switchToNewsDetails：event :) 
  
 
 
 
目前尚不清楚您尝试做什么，每个按钮的索引可以执行以下操作：
 
 
为每个按钮设置一个等于所需索引的标签属性
 $ b $在 switchToNewsDetails：方法中，您可以获取该索引并打开相应的缩写：
   - （void）switchToNewsDetails：（UIButton *）sender {
 [self openDetails：sender.tag]; 
 //或在这里打开逻辑
} 
  
  
 
 
I am using addTarget:action:forControlEvents like this:

[newsButton addTarget:self
action:@selector(switchToNewsDetails)
forControlEvents:UIControlEventTouchUpInside];


and I would like to pass parameters to my selector "switchToNewsDetails".
The only thing I succeed in doing is to pass the (id)sender by writing:
action:@selector(switchToNewsDetails:)


But I am trying to pass variables like integer values. Writing it this way doesn't work :

int i = 0;
[newsButton addTarget:self
action:@selector(switchToNewsDetails:i)
forControlEvents:UIControlEventTouchUpInside];


Writing it this way does not work either:

int i = 0;
[newsButton addTarget:self
action:@selector(switchToNewsDetails:i:)
forControlEvents:UIControlEventTouchUpInside];


Any help would be appreciated :)
解决方案
action:@selector(switchToNewsDetails:)
You do not pass parameters to switchToNewsDetails: method here. You just create a selector to make button able to call it when certain action occurs (touch up in your case). Controls can use 3 types of selectors to respond to actions, all of them have predefined meaning of their parameters:

with no parameters
action:@selector(switchToNewsDetails)

with 1 parameter indicating the control that sends the message
action:@selector(switchToNewsDetails:)

With 2 parameters indicating  the control that sends the message and the event that triggered the message: 
action:@selector(switchToNewsDetails:event:)

It is not clear what exactly you try to do, but considering you want to assign a specific details index to each button you can do the following:

set a tag property to each button equal to required index
in switchToNewsDetails: method you can obtain that index and open appropriate deatails:
- (void)switchToNewsDetails:(UIButton*)sender{
    [self openDetails:sender.tag];
    // Or place opening logic right here
}



                        
这篇关于将参数传递给addTarget：action：forControlEvents的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！