为了更好的理解通知，仿写了一个通知。其中用字典存储观察者，key是通知的名字，value是若干个观察者。这些观察者放到一个数组里。也就是value是数组。
YBNotification
@interface YBNotification : NSObject
@property(nonatomic,copy)NSString *name;
@property(nonatomic,strong,readonly) id object;
@property(nonatomic,readonly,copy)NSDictionary *userInfo;
- (instancetype)initWithName:(NSNotificationName)name object:(nullable id)object userInfo:(nullable NSDictionary *)userInfo;
+ (instancetype)notificationWithName:(NSNotificationName)aName object:(nullable id)anObject;
+ (instancetype)notificationWithName:(NSNotificationName)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo;
@end
#import "YBNotification.h"
@implementation YBNotification
- (instancetype)initWithName:(NSNotificationName)name object:(nullable id)object userInfo:(nullable NSDictionary *)userInfo
{
self = [super init];
if (self) {
_name = name;
_object = object;
_userInfo = userInfo;
}
return self;
}
+ (instancetype)notificationWithName:(NSNotificationName)aName object:(nullable id)anObject
{
return [self notificationWithName:aName object:anObject userInfo:nil];
}
+ (instancetype)notificationWithName:(NSNotificationName)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo
{
return [[self alloc]initWithName:aName object:anObject userInfo:aUserInfo];
}
@end
YBNotificationCenter
@interface YBNotificationCenter : NSObject
+ (YBNotificationCenter *)defaultCenter;
- (void)addObserver:(id)observer selector:(SEL)aSelector name:(nullable NSString *)aName object:(nullable id)anObject;
- (void)postNotification:(YBNotification *)notification;
- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject;
- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo;
- (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 (^)(YBNotification *note))block;
@end
#import "YBNotificationCenter.h"
typedef void(^OperationBlock)(YBNotification *notification);
@interface YBObserverModel : NSObject
@property (nonatomic, strong) id observer;
@property (nonatomic, assign) SEL selector;
@property (nonatomic, copy) NSString *notificationName;
@property (nonatomic, strong) id object;
@property (nonatomic, strong) NSOperationQueue *operationQueue;
@property (nonatomic, copy) OperationBlock block;
@end
@implementation YBObserverModel
@end
@interface YBNotificationCenter ()
@property (nonatomic, strong) NSMutableDictionary *observersDic;
@end
@implementation YBNotificationCenter
static YBNotificationCenter *instance = nil;
+ (instancetype)allocWithZone:(struct _NSZone *)zone
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [super allocWithZone:zone];
});
return instance;
}
- (id)copyWithZone:(NSZone *)zone
{
return instance;
}
+ (YBNotificationCenter *)defaultCenter
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc]init];
});
return instance;
}
- (instancetype)init
{
self = [super init];
if (self) {
_observersDic = [NSMutableDictionary dictionary];
}
return self;
}
- (void)addObserver:(id)observer selector:(SEL)aSelector name:(nullable NSString *)aName object:(nullable id)anObject
{
YBObserverModel *model = [YBObserverModel new];
model.observer = observer;
model.selector = aSelector;
model.notificationName = aName;
model.object = anObject;
// 按照key存储监听者的数组
NSMutableArray *modelArray = [self.observersDic objectForKey:aName];
if (!modelArray) {
modelArray = [NSMutableArray array];
}
[modelArray addObject:model];
[self.observersDic setObject:modelArray forKey:aName];
}
- (id <NSObject>)addObserverForName:(nullable NSString *)name object:(nullable id)obj queue:(nullable NSOperationQueue *)queue usingBlock:(void (^)(YBNotification *note))block
{
YBObserverModel *model = [YBObserverModel new];
model.notificationName = name;
model.object = obj;
model.operationQueue = queue;
model.block = block;
// 按照key存储监听者的数组
NSMutableArray *modelArray = [self.observersDic objectForKey:name];
if (!modelArray) {
modelArray = [NSMutableArray array];
}
[modelArray addObject:model];
[self.observersDic setObject:modelArray forKey:name];
return nil;
}
- (void)postNotification:(YBNotification *)notification
{
NSString *name = notification.name;
NSArray *modelArray = [self.observersDic objectForKey:name];
for (YBObserverModel *model in modelArray) {
id observer = model.observer;
SEL selector = model.selector;
if (model.operationQueue) {
[model.operationQueue addOperationWithBlock:^{
model.block(notification);
}];
}else{
[observer performSelector:selector withObject:notification];
}
}
}
- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject
{
[self postNotificationName:aName object:anObject userInfo:nil];
}
- (void)postNotificationName:(NSString *)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo
{
YBNotification *notification = [[YBNotification alloc]initWithName:aName object:anObject userInfo:aUserInfo];
[self postNotification:notification];
}
- (void)removeObserver:(id)observer
{
[self removeObserver:observer name:nil object:nil];
}
- (void)removeObserver:(id)observer name:(nullable NSString *)aName object:(nullable id)anObject
{
for (NSString *name in self.observersDic) {
NSMutableArray *modelArray = [self.observersDic objectForKey:name];
for (YBObserverModel *model in modelArray) {
if (model.observer == observer && [model.notificationName isEqualToString: aName] && model.object == anObject) {
[modelArray removeObject:model];
}
}
}
}
@end
demo
https://github.com/yinbowang/NSNotificationDemo
