ios - 在继续之前等待 AFHTTPRequestOperation 完成

Question

我正在尝试制作一个使用 AFHTTPClient 与 API 通信的 iOS 应用程序。第一步是对用户进行身份验证，为此，我使用以下代码:

-(void)authorize
{
    NSURLRequest *request = [httpClient requestWithMethod:@"POST" path:@"login.php" parameters:@{@"login": account.username, @"passwd":account.password}];

    AFHTTPRequestOperation *operation = [httpClient HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, id responseObject) {
        [httpClient setDefaultHeader:@"Token" value:[[operation.response allHeaderFields] objectForKey:@"CSRF-Token"]];
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"%@",error.localizedDescription);
    }];
    [httpClient enqueueHTTPRequestOperation:operation];
    [httpClient.operationQueue waitUntilAllOperationsAreFinished];
}

如您所见，我的代码从服务器响应中获取 token 并将其设置为所有 future 请求的默认 header 。

然后我使用 - (void)postPath:(NSString *)path parameters:(NSDictionary *)parameters success:success failure:failure 继续其他请求

但是当我使用调试器时，我发现那些在授权操作完成之前执行的其他请求，因此它们失败了，因为它们没有授权 token 。我添加了 [httpClient.operationQueue waitUntilAllOperationsAreFinished]; 但它似乎不起作用...

谢谢你的帮助

Answer 1

使用 dispatch semaphore .

-(void)authorize
{
    dispatch_semaphore_t done = dispatch_semaphore_create(0);
    NSURLRequest *request = [httpClient requestWithMethod:@"POST" path:@"login.php" parameters:@{@"login": account.username, @"passwd":account.password}];

    AFHTTPRequestOperation *operation = [httpClient HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, id responseObject) {
        [httpClient setDefaultHeader:@"Token" value:[[operation.response allHeaderFields] objectForKey:@"CSRF-Token"]];
        dispatch_semaphore_signal(done);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"%@",error.localizedDescription);
    }];
    [httpClient enqueueHTTPRequestOperation:operation];
    [httpClient.operationQueue waitUntilAllOperationsAreFinished];
    dispatch_semaphore_wait(done, DISPATCH_TIME_FOREVER);
}

请注意，这会阻止该方法返回，因此您需要确保它不在主/UI 线程上。