ios - NSJSONSerialization不起作用，NSUTF8StringEncoding起作用

我已经阅读了文档，教程和其他Stack Q＆A，并且对如何使用JSON而不是NSUTF8StringEncoding使NSJSONSerialization出现感到困惑，这是我需要将数据提取到NSDictionary或NSArray。我认为从我的网址返回的NSData格式存在问题吗？

编辑这是错误:错误域= NSCocoaErrorDomain代码= 3840“该操作无法完成。(可可错误3840。)”(结束时是垃圾。)UserInfo = 0x8aabc30

NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.sampleURL.com"]
                                          cachePolicy:NSURLRequestUseProtocolCachePolicy
                                      timeoutInterval:15.0];

NSMutableData* responseData = [NSMutableData dataWithCapacity: 0];

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    //this works, and have NSLog below
    responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"string %@", responseString);

    [responseData appendData:data];
    responseData = [[NSMutableData alloc] initWithData:data];

     //this is null in NSLog
    NSError * error;
    NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:data   options:NSJSONReadingMutableContainers|NSJSONReadingAllowFragments error:&error];

    NSLog(@"jsonDict dict %@",jsonDict);
}

调试控制台:

 2014-03-11 07:41:58.233 WBPC[7845:a0b] string   {"id":"a1","session":"General","name":"Exhibitor Setup Begins","startTime":"0900","details":"9am Exhibitor Hall","png":"image","speaker1":"Johnson","speaker2":"Nelson","speaker3":""}{"id":"b1","session":"General","name":"Conference Registration","startTime":"1000","details":"10am Noon Upper Level Lobby","png":"image","speaker1":"Jackson","speaker2":"","speaker3":""}
 2014-03-11 07:41:58.236 WBPC[7845:a0b] jsonDict (null)

最佳答案

您的JSON格式不正确。您告诉我们这是(为清晰起见添加了空格和换行符):

{
    "id": "a1",
    "session": "General",
    "name": "Exhibitor Setup Begins",
    "startTime": "0900",
    "details": "9am Exhibitor Hall",
    "png": "image",
    "speaker1": "Johnson",
    "speaker2": "Nelson",
    "speaker3": ""
}{
    "id": "b1",
    "session": "General",
    "name": "Conference Registration",
    "startTime": "1000",
    "details": "10am Noon Upper Level Lobby",
    "png": "image",
    "speaker1": "Jackson",
    "speaker2": "",
    "speaker3": ""
}

缺少两个字典条目之间的逗号，并且缺少应包装JSON的[和]。如果确实是字典条目的数组，则应为:

[
    {
        "id": "a1",
        "session": "General",
        "name": "Exhibitor Setup Begins",
        "startTime": "0900",
        "details": "9am Exhibitor Hall",
        "png": "image",
        "speaker1": "Johnson",
        "speaker2": "Nelson",
        "speaker3": ""
    },
    {
        "id": "b1",
        "session": "General",
        "name": "Conference Registration",
        "startTime": "1000",
        "details": "10am Noon Upper Level Lobby",
        "png": "image",
        "speaker1": "Jackson",
        "speaker2": "",
        "speaker3": ""
    }
]

如果要检查JSON，可以访问http://jsonlint.com。另外，如果您检查了error返回的JSONObjectWithData对象，它将为您指明正确的方向。

您应该查看如何生成此JSON。看起来它必须是手动生成的。例如，如果是从PHP页面生成的，则应使用 json_encode ，而不是手动生成JSON。

顺便说一句，您正在尝试将结果解析为didReceiveData。在connectionDidFinishLoading之前，您不应该尝试解析。您的didReceiveData应该仅将data附加到NSMutableData对象。解析应该推迟到connectionDidFinishLoading为止。