文章写于 2018-6-24, 阅读的是 AFNetworking 3.2.1
之前看了很多别人写的文章, 是按着别人的思路学习的, 感觉以我现在水平, 可以有自己的理解了. 网上搜到的文章大部分都是主流程, 我已经比较熟悉主流程了, 这里会写一些细节
AFHTTPSessionManager.m
204
if (serializationError) {
if (failure) {
dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
failure(nil, serializationError);
});
}
return nil;
}
无法生成request时, AF会把失败的block放到一个并发队列(如果有的话)/主队列中. YTKNetwork初始化了这个并发队列
AFURLRequestSerialization.m
370
// 只初始化一次的静态数组, 可以这么写
static NSArray * AFHTTPRequestSerializerObservedKeyPaths() {
static NSArray *_AFHTTPRequestSerializerObservedKeyPaths = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_AFHTTPRequestSerializerObservedKeyPaths = @[NSStringFromSelector(@selector(allowsCellularAccess)), NSStringFromSelector(@selector(cachePolicy)), NSStringFromSelector(@selector(HTTPShouldHandleCookies)), NSStringFromSelector(@selector(HTTPShouldUsePipelining)), NSStringFromSelector(@selector(networkServiceType)), NSStringFromSelector(@selector(timeoutInterval))];
});
return _AFHTTPRequestSerializerObservedKeyPaths;
}
观察某个属性名的时候, 不要写成@"allowsCellularAccess"这种形式, 要充分利用编译器, 这样写
NSStringFromSelector(@selector(allowsCellularAccess))
371
self.mutableObservedChangedKeyPaths
AF把AFHTTPRequestSerializerObservedKeyPaths里面变化的属性都放到mutableObservedChangedKeyPaths 这里了
246
[self addObserver:self forKeyPath:keyPath options:NSKeyValueObservingOptionNew context:AFHTTPRequestSerializerObserverContext];
// context的正确初始化方式
static void *AFHTTPRequestSerializerObserverContext = &AFHTTPRequestSerializerObserverContext;
530
+ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
if ([AFHTTPRequestSerializerObservedKeyPaths() containsObject:key]) {
return NO;
}
return [super automaticallyNotifiesObserversForKey:key];
}
AFHTTPRequestSerializerObservedKeyPaths 这个数组里的属性 设置为手动触发KVO(学要手动调用willChange和didChange方法触发)
