JSON写入中的无效顶级类型 [英] Invalid top-level type in JSON write

问题描述

我正在尝试创建一个简单的JSON对象，但仍然出现错误，并且我知道代码中有什么问题:

I'm trying to create a simple JSON object but I still get error and I know what's wrong in my code:

NSString *vCard = [BRContacts getContacts]; // this is just a string, could be nil
NSDictionary *JSONdic = nil;
if (vCard)
{
    JSONdic = [NSDictionary dictionaryWithObjectsAndKeys:@"1",@"status",vCard,@"data", nil];
}
else
{
    JSONdic = [NSDictionary dictionaryWithObjectsAndKeys:@"0",@"status",@"vCard is empty",@"error", nil];
}
NSError *error = nil;
NSData *JSONData = [NSJSONSerialization dataWithJSONObject:JSONdic options:NSJSONWritingPrettyPrinted error:&error];
return [GCDWebServerDataResponse responseWithJSONObject:JSONdata];

例外是

JSON写入中的无效顶级类型

Invalid top-level type in JSON write

我也检查了JSONdic，在每种情况下它都不为零. 有什么建议吗?

I checked also JSONdic and it's not nil in every case. Any suggestions?

推荐答案

好，我解决了.这是与此行相关的问题:

Ok I solved. It was a problem related to this line:

return [GCDWebServerDataResponse responseWithJSONObject:JSONdata];

此响应 GCDWebServer 不需要JSON NSData，但不需要NSDictionary:错误仅是因为responseWithJSONObject处理用于创建JSON对象的输入(并且我传递了一个JSON预处理"对象).所以我的错误与我的初始代码无关，所以我现在才更新它以供将来参考，我使用以下方法解决了该问题:

this response of GCDWebServer doesn't want a JSON NSData but a NSDictionary: the error is just because responseWithJSONObject process the input for create a JSON object (and I passed a JSON "pre-processed" object). So my error is not related to my initial code so I updated it just now for future reference, I solved using:

return [GCDWebServerDataResponse responseWithJSONObject:JSONdic]; 

根据文档类似问题，请务必遵循以下规则:

According to the documentation for similar problem be sure to follow this rules:

可能转换为JSON的对象必须具有以下内容 属性:

An object that may be converted to JSON must have the following properties:

• 顶级对象是NSArray或NSDictionary.
• 所有对象都是 NSString，NSNumber，NSArray，NSDictionary或NSNull的实例.
• 所有字典键都是NSString的实例.
• 数字不是NaN或无穷大.

• The top level object is an NSArray or NSDictionary.
• All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.
• All dictionary keys are instances of NSString.
• Numbers are not NaN or infinity.

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