通知中心 － NSNotificationCenter

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NS_ASSUME_NONNULL_BEGIN

/**************** Notifications ****************/

// 通知，被发送，被接受。

@interface NSNotification : NSObject <NSCopying, NSCoding>

通知的名字 

@property (readonly, copy) NSString *name;

具体某一个对象。

@property (nullable, readonly, retain) id object;

参数信息

@property (nullable, readonly, copy) NSDictionary *userInfo;

初始化一个 通知 对象

name     将来又谁来接受，（发送给谁）

object    具体的某一个对象，或者为nil，

userInfo  附加的信息，参数

- (instancetype)initWithName:(NSString *)name object:(nullable id)object userInfo:(nullable NSDictionary *)userInfo NS_AVAILABLE(10_6, 4_0) NS_DESIGNATED_INITIALIZER;

- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;

@end

@interface NSNotification (NSNotificationCreation)

初始化一个通知 

+ (instancetype)notificationWithName:(NSString *)aName object:(nullable id)anObject;

同上

+ (instancetype)notificationWithName:(NSString *)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo;

- (instancetype)init /*NS_UNAVAILABLE*/; /* do not invoke; not a valid initializer for this class */

@end

/**************** Notification Center ****************/

@interface NSNotificationCenter : NSObject {

    @package

    void * __strong _impl;

    void * __strong _callback;

    void *_pad[11];

}

 单利，获取通知中心，来注册，或者发送通知。一定是 先注册，后发送。不然，无效。

+ (NSNotificationCenter *)defaultCenter;

注册通知，（监听通知） 

- (void)addObserver:(id)observer selector:(SEL)aSelector name:(nullable NSString *)aName object:(nullable id)anObject;

 发送通知

- (void)postNotification:(NSNotification *)notification;

- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject;

- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo;

移除通知 

- (void)removeObserver:(id)observer;

- (void)removeObserver:(id)observer name:(nullable NSString *)aName object:(nullable id)anObject;

- (id <NSObject>)addObserverForName:(nullable NSString *)name object:(nullable id)obj queue:(nullable NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *note))block NS_AVAILABLE(10_6, 4_0);

    // The return value is retained by the system, and should be held onto by the caller in

    // order to remove the observer with removeObserver: later, to stop observation.

@end

NS_ASSUME_NONNULL_END

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通知中心 － NSNotificationCenter

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原文地址：http://www.cnblogs.com/kinghx/p/5351016.html