Question

我想在NSNotification中将对象发送到选择器。我的意思是，我有3个按钮，点击每个按钮我正在注册通知，当该事件发生时，我正在调用一个选择器，在那个选择器中我想找出哪个按钮用户已单击，因为我对所有3个按钮都有共同的操作。

-(void)allThreeButtonAction:(sender)id
{
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(performSomeOperationWhenEventOccur) name:@"EventCompletedNotification" object:nil];
}

//发生了一些事件，所以我发送了通知

[[NSNotificationCenter defaultCenter] postNotificationName:@"EventCompletedNotification" object:nil];

//通知方法

-(void)performSomeOperationWhenEventOccur
{
    //Here I want to know which button is pressed.
}

我希望我很清楚。

Answer 1

您可能需要查看NSNotificationCenter documentation

中的postNotificationName:object:userInfo:

您只需发送一个UserInfo，其中包含您在选择器中检索的按钮（最简单的指向按钮的指针）所需的任何内容。

您的选择者签名应该收到通知：

- (void)performSomeOperationWhenEventOccur:(NSNotification*) notification:(NSNotification*) notification
{
    // Use [notification userInfo] to determine which button was pressed...
}

注册时不要忘记修改选择器名称：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(performSomeOperationWhenEventOccur:) name:@"EventCompletedNotification" object:nil];

Answer 2

添加通知观察者时无法传递对象，因此您必须存储在某处按下的按钮：

-(void)allThreeButtonAction:(id)sender
{
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(performSomeOperationWhenEventOccur) name:@"EventCompletedNotification" object:nil];
   self.buttonPressed = sender;
}

然后您可以在通知处理程序中阅读它：

-(void)performSomeOperationWhenEventOccur
{
    if ( self.buttonPressed = self.button1 )
        ...
}

Answer 3

以下代码段将为您提供帮助。

<强> Button1的

   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(performSomeOperationWhenEventOccur:) name:@"button1" object:button1];

<强>将Button2

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(performSomeOperationWhenEventOccur:) name:@"button2" object:button2];

将方法更改为以下

- (void) performSomeOperationWhenEventOccur:(NSNotification *) notification
{
    if ([[notification name] isEqualToString:@"button1"])
    {
        NSButton *button1=[notification button1];
        NSLog (@"Successfully received the test notification! from button1");
    }
     else
    {
        NSButton *button2=[notification button2]; 
        NSLog (@"Successfully received the test notification! from button2");
    } 
}

如何在NSNotification中发送对象？

3 个答案: