Question

是否可以通过NotificationCenter列出对象正在观察的所有通知？

Answer 1

我认为这可能是一个＆＃34; hacky＆＃34;方式：使用Swizzling观察NSNotificationCenter.addObserver方法。

@implementation NSNotificationCenter (Swizzling)

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];

        SEL originalSelector = @selector(addObserver:selector:name:object:);
        SEL swizzledSelector = @selector(swizzling_addObserver:selector:name:object:);

        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);

        BOOL didAddMethod =
        class_addMethod(class,
                        originalSelector,
                        method_getImplementation(swizzledMethod),
                        method_getTypeEncoding(swizzledMethod));

        if (didAddMethod) {
            class_replaceMethod(class,
                                swizzledSelector,
                                method_getImplementation(originalMethod),
                                method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}

- (void)swizzling_addObserver:(id)observer selector:(SEL)aSelector name:(NSNotificationName)aName object:(id)anObject {
    //implement code here to store all notifications.

    //then call original method (read in the link below to understand why we call **swizzling_addObserver** but not **addObserver**
    [self swizzling_addObserver:observer selector:aSelector name:aName object:anObject];
}

要了解有关调配的更多信息，请阅读以下文章： http://nshipster.com/method-swizzling/

Answer 2

您可以通过解析[[NSNotificationCenter defaultCenter] debugDescription]并搜索对象地址来实现：

名称，对象，观察者，选项
NSWindowWillEnterFullScreenNotification，0x7fffb685e8e0， 0x6000001003f0,1400
_NSWindowDidChangeContentsHostedInLayerSurfaceNotification，0x7fffb685e8e0,0x6180000a4680,1400
NSAntialiasThresholdChangedNotification，0x7fffb685e8e0， 0x6080001e0300,1400
kCFLocaleCurrentLocaleDidChangeNotification， 0x7fffb685e8e0,0x7fffb685e9c0,1001
some_string，0x7fffb685e8e0， 0x600000000210,1400
...

如何列出对象正在观察的所有通知？

2 个答案: