NSDictionary 被视为布尔值 - 无法调试

Question

NSDictionary *tokenData = [[responseDict objectForKey:@"data"] objectForKey:@"multipass"];
dispatch_async(dispatch_get_main_queue(), ^{
    NSString *card = [NSString stringWithFormat:@"%@-%@",
        [[UserAccount sharedInstance] cardNumber],
        [tokenData objectForKey:@"CardPhoneToken"]]; //<-- problem
});

从昨天开始，我一直在与这行代码作斗争。我正在从服务器获取 JSON 提要，我的问题是，有十分之一的 tokenData 返回 0 而不是 Dictionary我不知道为什么。当它以0 返回时，它也被编译器视为布尔值（也不知道为什么），我收到错误-[NSCFBoolean objectForKey:]: unrecognized selector sent to instance 0x81aa20

我试过做这样的事情 if(!tokenData) { NSLog(@"This is going to crash"); } 但是当tokenData 返回0 时，if 不会被调用。

esponseDict JSON 我得到： { code = 200; data = { multipass = { CardPhoneBarcodeToken = 562431; CardPhoneToken = 23221; errorMessage = ""; operationResult = 0; }; }; }

这是崩溃前的样子：{ code = 200; data = { multipass = 0; }; }

更新：如果tokenData 不是NSDictionary，我已经设法采取措施，现在我面临else 部分的另一个问题。如果 tokenData 不是 NSDictionary ，我该如何重新加载？我尝试调用 *tokenData = [[responseDict objectForKey:@"data"] objectForKey:@"multipass"];在 else 里面，但我不断得到 tokenData = 0 谢谢

Answer 1

我会在解析之前检查tokenData 是否为NSDictionary。

-(void)loadData
{
    NSDictionary *tokenData = [[responseDict objectForKey:@"data"] objectForKey:@"multipass"];
    dispatch_async(dispatch_get_main_queue(), ^{
        NSString *cardPhoneToken = @"";
        if( [tokenData isKindOfClass:[NSDictionary class]] ){
            retryCount = 0;
            cardPhoneToken = [tokenData objectForKey:@"CardPhoneToken"];
        } else {
            NSLog(@"failed to load data, retrying...");
            retryCount++;
            if( retryCount < 5 ){
                [self loadData];
                return;
            } else {
                NSLog(@"failed after 5 retries");
            }

        }
        NSString *card = [NSString stringWithFormat:@"%@-%@",
                          [[UserAccount sharedInstance] cardNumber],
                          cardPhoneToken];

    });
}

Answer 2

听起来很熟悉。 :)

将块更改为：

^{
    NSString *card;
    if ([tokenData isKindOfClass [NSDictionary class]) {

      card = [NSString stringWithFormat:@"%@-%@",
          [[UserAccount sharedInstance] cardNumber],
          [tokenData objectForKey:@"CardPhoneToken"]]; // <<-- No Problem anymore
     } else {
       // deal with the situation. Probably do: 
      card = [NSString stringWithFormat:"%@-no phone number given", [UserAccount sharedInstance] cardNumber]];
}

替代方案：

^{
    id cardPhoneToken;
    if ([tokenData]) {
       cardPhoneToken = [tokenData objectForKey:@"CardPhoneToken"];
    } else {
       cardPhoneToken = @"no Phone Token"; // Or what ever you think is appropriate
    }
    NSString *card = [NSString stringWithFormat:@"%@-%@",
        [[UserAccount sharedInstance] cardNumber],
        cardPhoneToken]; // <<-- No Problem anymore

}