AFNetworking返回功能

Question

我使用AFNetworking框架https://github.com/AFNetworking/AFNetworking。 一切都好，但函數返回Null，但一切都很好NSLog返回Null。 可能是什麼原因？

-(NSString *)cook 
{ 
    __block NSString *fecho =nil; 

    NSURL *baseURL = [NSURL URLWithString:@"http://google.com"]; 

    AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:baseURL]; 

    [httpClient defaultValueForHeader:@"Accept"]; 

    NSMutableURLRequest *request = [httpClient requestWithMethod:@"GET" path:@"" parameters:nil]; 

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request]; 

    [httpClient registerHTTPOperationClass:[AFHTTPRequestOperation class]]; 

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) 
    { 
     fecho = [[operation.response allHeaderFields] valueForKeyPath:@"Date"]; 

     NSLog(@"%@",fecho); 
    } 
            failure:^(AFHTTPRequestOperation *operation, NSError *error) 
    { 
     fecho = @"errr"; 
    }]; 

    [request setTimeoutInterval:20.0]; 
    [operation start]; 

    return fecho; 
} 

非常感謝！

Answer 1

變化-(NSString *)cook到

- (void)cookOnCompletion:(void (^)(NSString *errorMessage))completion { 

    NSURL *baseURL = [NSURL URLWithString:@"http://google.com"]; 

    AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:baseURL]; 

    [httpClient defaultValueForHeader:@"Accept"]; 

    NSMutableURLRequest *request = [httpClient requestWithMethod:@"GET" path:@"" parameters:nil]; 

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request]; 

    [httpClient registerHTTPOperationClass:[AFHTTPRequestOperation class]]; 

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) 
    { 
     NSString *fecho = [[operation.response allHeaderFields] valueForKeyPath:@"Date"]; 

     completion(fecho); 
    } 
           failure:^(AFHTTPRequestOperation *operation, NSError *error) 
    { 
     NSString *error = @"errr"; 
     completion(error); 
    }]; 

    [request setTimeoutInterval:20.0]; 
    [operation start]; 
} 

，並呼籲cookOnCompletion:像

[self cookOnCompletion:^(NSString *response){ 
    NSLog(@"%@",response); 
}];