objective-c Cocoa 自定义通知示例
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Cocoa Custom Notification Example
提问by mattdwen
Can someone please show me an example of a Cocoa Obj-C object, with a custom notification, how to fire it, subscribe to it, and handle it?
有人可以向我展示一个 Cocoa Obj-C 对象的示例，带有自定义通知，如何触发、订阅和处理它？
回答by Jason Coco
@implementation MyObject
// Posts a MyNotification message whenever called
- (void)notify {
[[NSNotificationCenter defaultCenter] postNotificationName:@"MyNotification" object:self];
}
// Prints a message whenever a MyNotification is received
- (void)handleNotification:(NSNotification*)note {
NSLog(@"Got notified: %@", note);
}
@end
// somewhere else
MyObject *object = [[MyObject alloc] init];
// receive MyNotification events from any object
[[NSNotificationCenter defaultCenter] addObserver:object selector:@selector(handleNotification:) name:@"MyNotification" object:nil];
// create a notification
[object notify];
For more information, see the documentation for NSNotificationCenter.
有关更多信息，请参阅NSNotificationCenter的文档。
回答by mracoker
Step 1:
第1步：
//register to listen for event
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(eventHandler:)
name:@"eventType"
object:nil ];
//event handler when event occurs
-(void)eventHandler: (NSNotification *) notification
{
NSLog(@"event triggered");
}
Step 2:
第2步：
//trigger event
[[NSNotificationCenter defaultCenter]
postNotificationName:@"eventType"
object:nil ];
回答by Grigori A.
Make sure to unregister notification (observer) when your object is deallocated. Apple documentation states: "Before an object that is observing notifications is deallocated, it must tell the notification center to stop sending it notifications".
当您的对象被解除分配时，请确保取消注册通知（观察者）。Apple 文档指出：“在释放正在观察通知的对象之前，它必须告诉通知中心停止向其发送通知”。
For Local Notifications the next code is applicable:
对于本地通知，下一个代码适用：
[[NSNotificationCenter defaultCenter] removeObserver:self];
And for observers of distributed notifications:
对于分布式通知的观察者：
[[NSDistributedNotificationCenter defaultCenter] removeObserver:self];
