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AFNetworking代碼有一些地方,其中__block用於沒有明顯需要更改對象的方法中的對象。例如,在AFHTTPSessionManager中,GET調用在任務對象上使用__block。任何想法爲什麼?在AFNetworking中,爲什麼有些返回對象聲明爲__block類型?
- (NSURLSessionDataTask *)GET:(NSString *)URLString
parameters:(NSDictionary *)parameters
success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure
{
NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:@"GET" URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters];
__block NSURLSessionDataTask *task = [self dataTaskWithRequest:request completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
if (error) {
if (failure) {
failure(task, error);
}
} else {
if (success) {
success(task, responseObject);
}
}
}];
[task resume];
return task;
}
同樣在其他類中,__block用於對象,如下面顯示的憑證對象。
- (void)URLSession:(NSURLSession *)session
didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler
{
NSURLSessionAuthChallengeDisposition disposition = NSURLSessionAuthChallengePerformDefaultHandling;
__block NSURLCredential *credential = nil;
if (self.sessionDidReceiveAuthenticationChallenge) {
disposition = self.sessionDidReceiveAuthenticationChallenge(session, challenge, &credential);
} else {
if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
if ([self.securityPolicy evaluateServerTrust:challenge.protectionSpace.serverTrust]) {
credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
if (credential) {
disposition = NSURLSessionAuthChallengeUseCredential;
} else {
disposition = NSURLSessionAuthChallengePerformDefaultHandling;
}
} else {
disposition = NSURLSessionAuthChallengeCancelAuthenticationChallenge;
}
} else {
disposition = NSURLSessionAuthChallengePerformDefaultHandling;
}
}
if (completionHandler) {
completionHandler(disposition, credential);
}
}
對我來說這看起來像一個錯誤。至少第一個是。 – CodaFi