JSON 字典中的键

发布于 2024-12-02 05:59:33 字数 1055 浏览 2 评论 0原文

我正在导入 JSON 字典。我需要知道使用它的按键名称。

字典加载数据正常：

   - (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[connection release];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
[responseData release];    
  NSDictionary *results = [responseString JSONValue];
  NSLog(@"tenga: %@",results);

但是当我尝试获取键的名称时，应用程序崩溃：

NSArray * keys = [results allKeys];
NSLog(@"keys: %@",keys); ...}

错误消息：

[__NSArrayM allKeys]：无法识别的选择器发送到实例 0x5a16b30 2011-08-30 22:52:26.171 Twitter Search[1906:207] * 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“-[__NSArrayM allKeys]：无法识别的选择器发送到实例 0x5a16b30 '

为什么 allKeys 不起作用？

如何获取键的名称以便我可以开始使用对象？

编辑

我使用 http://code.google.com/p/json-framework Stig Brautaset json 框架

原文

I'm importing a JSON dictionary. I need to know the name of the keys to work with it.

The dictionary is loading the data ok:

   - (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[connection release];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
[responseData release];    
  NSDictionary *results = [responseString JSONValue];
  NSLog(@"tenga: %@",results);

but when I try to get the names of the keys the app crashes:

NSArray * keys = [results allKeys];
NSLog(@"keys: %@",keys); ...}

error message:

[__NSArrayM allKeys]: unrecognized selector sent to instance 0x5a16b30
2011-08-30 22:52:26.171 Twitter Search[1906:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM allKeys]: unrecognized selector sent to instance 0x5a16b30'

Why is allKeys not working?

How do I get the names for my keys so I can start working with the objects?

edit

Im using the http://code.google.com/p/json-framework Stig Brautaset json framework

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甜味超标? 2024-12-09 05:59:33

您从中获取 JSON 字符串的 URL 为您提供了一个数组，而不是一个对象，即它看起来类似于：

[ { "foo1" : "bar1" }, { "foo2" : "bar2" },... ]

请注意括号 [ ]。在这种情况下，您的 JSON 解析器会为您提供一个 NSArray 作为顶级 (Objective-C) 对象。您需要一些逻辑，例如：

id results = [responseString JSONValue];
if ([results isKindOfClass: [NSArray class]])
{
    // probably iterate through whtever is in it
}
else if ([results isKindOfClass: [NSDictionary class]])
{
    // dictionary at the top level.  Hooray!
}
else
{
    // something went horribly wrong, deal with it.
}

The URL that you obtained that JSON string from gave you an array, not an object i.e. it looked something like:

[ { "foo1" : "bar1" }, { "foo2" : "bar2" },... ]

Note the brackets [ ]. In that situation, your JSON parser gave you an NSArray as the top level (Objective-C) object. You need some logic like:

id results = [responseString JSONValue];
if ([results isKindOfClass: [NSArray class]])
{
    // probably iterate through whtever is in it
}
else if ([results isKindOfClass: [NSDictionary class]])
{
    // dictionary at the top level.  Hooray!
}
else
{
    // something went horribly wrong, deal with it.
}

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