iOS 等待异步操作后 return 值

需求是:一个函数 等AFNetwork 网络 请求完成后,修改返回值,并继续执行函数,并返回值.

- (BOOL)Action_alertAgreement
{
    
    dispatch_semaphore_t signal = dispatch_semaphore_create(0);

    __block BOOL returnValue = NO;
    HWHttpRequestOperationManager *httpManager = [HWHttpRequestOperationManager baseManager];
    httpManager.completionQueue = dispatch_get_global_queue(0, 0);
    [httpManager postHttpRequest:kGetOrgAgreementInfo parameters:nil queue:nil success:^(NSDictionary * _Nullable responseObject) {
            dispatch_async(dispatch_get_main_queue(), ^{
                [Utility_new showToastWithMessage:remark];
            });
            returnValue = NO;
        }
        dispatch_semaphore_signal(signal);

    } failure:^(NSString * _Nullable code, NSString * _Nullable error) {
        returnValue = NO;
        dispatch_semaphore_signal(signal);
    }];
    dispatch_semaphore_wait(signal, DISPATCH_TIME_FOREVER);
    return returnValue;
}

关键的一步是设置httpManager.completionQueue = dispatch_get_global_queue(0, 0);要不然会阻塞主线程.并且如果要在AFNetwork的回调中操作UI,要切换到主线程. HWHttpRequestOperationManager 是对AFNetwork的进一步封装,可以忽略.