关于ios：通过Objective-C中的NSNotificationCenter发送和接收消息？


Send and receive messages through NSNotificationCenter in Objective-C?

我正试图通过Objective-C中的NSNotificationCenter发送和接收消息。但是，我还没有找到任何关于如何做到这一点的例子。您如何通过NSNotificationCenter发送和接收消息？

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@implementation TestClass

- (void) dealloc
{
    // If you don't remove yourself as an observer, the Notification Center
    // will continue to try and send notification objects to the deallocated
    // object.
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];
}

- (id) init
{
    self = [super init];
    if (!self) return nil;

    // Add this instance of TestClass as an observer of the TestNotification.
    // We tell the notification center to inform us of"TestNotification"
    // notifications using the receiveTestNotification: selector. By
    // specifying object:nil, we tell the notification center that we are not
    // interested in who posted the notification. If you provided an actual
    // object rather than nil, the notification center will only notify you
    // when the notification was posted by that particular object.

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

    return self;
}

- (void) receiveTestNotification:(NSNotification *) notification
{
    // [notification name] should always be @"TestNotification"
    // unless you use this method for observation of other notifications
    // as well.

    if ([[notification name] isEqualToString:@"TestNotification"])
        NSLog (@"Successfully received the test notification!");
}

@end

…在另一个班级的其他地方…

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- (void) someMethod
{

    // All instances of TestClass will be notified
    [[NSNotificationCenter defaultCenter]
        postNotificationName:@"TestNotification"
        object:self];

}
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扩展Dreamlax的例子…如果您想与通知一起发送数据

张贴代码：

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NSDictionary *userInfo =
[NSDictionary dictionaryWithObject:myObject forKey:@"someKey"];
[[NSNotificationCenter defaultCenter] postNotificationName:
                       @"TestNotification" object:nil userInfo:userInfo];

在遵守准则时：

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- (void) receiveTestNotification:(NSNotification *) notification {

    NSDictionary *userInfo = notification.userInfo;
    MyObject *myObject = [userInfo objectForKey:@"someKey"];
}
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