IOS用GCD调接口

本文以UIActivityIndicatorView为例，有没有同学试过调接口，调接口的时候会不会想要有个UIActivityIndicatorView去转圈圈来表示正在等待呢？但是你如果直接调接口的话，即使你用UIActivityIndicatorView ，会不会怎么也无法显示呢？ 如果遇到这种情况，用GCD就可以，不过好麻烦就是了…… 

 

- (IBAction)queryUser:(id)sender
{
    [telephoneTextField resignFirstResponder];
    
    //开始转圈圈
    [indicator setHidden:NO];
    [indicator setHidesWhenStopped:YES];
    [indicator startAnimating];//转圈圈
    //采用GCD，如果调接口成功或者失败，圈圈停止
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSString *telephone = telephoneTextField.text;
        if ([telephone length] == 0)
        {
            //执行主线程
            dispatch_async(dispatch_get_main_queue(),  ^{
                UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"业务号码不能为空" message:@"请重新输入条件查询！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                [alertView show];
                [alertView release];
                
                [indicator stopAnimating];//停止圈圈
            });
            return;
        }
        //调用接口
        UserQueryBO *userQueryBO = [[UserQueryBO alloc] init];
        NSDictionary *resultList = [userQueryBO queryUser:telephone forUser:nil];
//接口返回值
        NSString *returnCode = [NSString stringWithFormat:@""];
        NSString *message= [NSString stringWithFormat:@""];
        NSString *resultInfo= [NSString stringWithFormat:@""];
        if (resultList != nil)
        {
            returnCode = [resultList objectForKey:@"ReturnCode"];
            message = [resultList objectForKey:@"Message"];
            resultInfo = [resultList objectForKey:@"ResultInfo"];
            //NSLog(@"%@", resultInfo);
        }
        if ([returnCode isEqualToString:@"0"])
        {
            if ([resultInfo length] > 0)
            {
                //成功调用主线程，利用主线程里navigationController去打开新页面
                dispatch_async(dispatch_get_main_queue(),  ^{
                    UserQueryShowVC *userQueryShowVC = [[UserQueryShowVC alloc] init];
                    userQueryShowVC.userInfo = resultInfo;
                    [self.navigationController pushViewController:userQueryShowVC animated:YES];
                    self.navigationController.title = @"用户查询详情";
                    [userQueryShowVC release];
                });
                
            }
            else
            {
                //接口调用失败，利用主线程打开输入框
                dispatch_async(dispatch_get_main_queue(),  ^{
                    UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"没查询到相关用户信息" message:@"请重新输入条件查询！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                    [alertView show];
                    [alertView release];
                    [indicator stopAnimating];//停止圈圈
                });
            }
        }
        else
        {
            //接口调用失败，利用主线程打开输入框
            dispatch_async(dispatch_get_main_queue(),  ^{
                UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"查询失败" message:[@"请重新输入条件查询！失败信息：" stringByAppendingString:message] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
                [alertView show];
                [alertView release];
                [indicator stopAnimating];//停止圈圈
            });
        }
        //[resultInfo release];
        //[message release];
        //[returnCode release];
        [userQueryBO release];
        //这里，保险起见，再停止圈圈……
        dispatch_async(dispatch_get_main_queue(),  ^{
            
            [indicator stopAnimating];
        });
    });
    
}

 代码如上，用//采用GCD

    dispatch_async(dispatch_get_global_queue(0, 0), ^{});将接口逻辑放在这里，如果需要停止圈圈或者弹出对话框，则用

dispatch_async(dispatch_get_main_queue(), ^{ 

            [indicator stopAnimating];

 

        });

去会写数据到主线程。

 

记得，不这样的话会报错的说