需要生成的 JSON 文档与 iOS 中 NSMutableDictionary 中插入的对象的顺序相同

我正在从 NSMutableDictionary 生成一个 JSON 文档，该文档由指向 NSStrings 的键以及两个依次指向其他 NSMutableDictionary 的键组成。我的问题是，当我输出 JSON 文档时，我注意到 JSON 文档具有我以不同顺序插入 NSMutableDictionary 中的对象。例如，我当前的输出如下所示：

JSON Output: {
  "devicetype" : "iPhone Simulator",
  "os" : "6.0",
  "test_results" : [
    {
      "date" : "2012-12-25T20:38:09",
      "name" : "Test 1",
      "result" : "Fail"
    },
    {
      "date" : "2012-12-25T20:38:11",
      "name" : "Test 2",
      "result" : "Pass"
    },
    {
      "date" : "2012-12-25T20:38:13",
      "name" : "Test 3",
      "result" : "Pass"
    },
    {
      "date" : "2012-12-25T20:38:19",
      "name" : "Test 4",
      "result" : "Fail"
    }
  ],
  "devicename" : "?????",
  "reports" : [

  ],
  "device_id" : "bb88413b178b4ef77830d385b9a4bd6d",
  "platform" : "iPhone OS"
}

但我希望输出看起来像这样：

JSON Output: {
  "devicetype" : "iPhone Simulator",
  "os" : "6.0",
  "devicename" : "?????",
  "device_id" : "bb88413b178b4ef77830d385b9a4bd6d",
  "platform" : "iPhone OS"

  "test_results" : [
    {
      "date" : "2012-12-25T20:38:09",
      "name" : "Test 1",
      "result" : "Fail"
    },
    {
      "date" : "2012-12-25T20:38:11",
      "name" : "Test 2",
      "result" : "Pass"
    },
    {
      "date" : "2012-12-25T20:38:13",
      "name" : "Test 3",
      "result" : "Pass"
    },
    {
      "date" : "2012-12-25T20:38:19",
      "name" : "Test 4",
      "result" : "Fail"
    }
  ],

  "reports" : [

  ],
}

我创建 JSON 文档的代码如下所示：

NSMutableArray* reports = [NSMutableArray array];    
NSMutableArray* results = [NSMutableArray array];


for (TestResult *testObject in testResultArray) {

        if ([[DataModel sharedInstance] getScore:testObject.score] == @"Not Tested") {

            NSMutableDictionary *naTest = [NSMutableDictionary dictionary];
            [naTest setObject:testObject.testName forKey:@"name"];
            [naTest setObject:testObject.dateStamp forKey:@"date"];

            [reports addObject:naTest];

        }

        else {

            NSMutableDictionary *fullTest = [NSMutableDictionary dictionary];
            NSString *score = [[DataModel sharedInstance] getScore:testObject.score];
            [fullTest setObject:score forKey:@"result"];
            [fullTest setObject:testObject.testName forKey:@"name"];
            [fullTest setObject:testObject.dateStamp forKey:@"date"];


            [results addObject:fullTest];

        }

    }

    NSMutableDictionary *mainDoc = [NSMutableDictionary dictionary];
    [mainDoc setObject:udid forKey:@"device_id"];
    [mainDoc setObject:systemName forKey:@"platform"];
    [mainDoc setObject:systemVersion forKey:@"os"];
    [mainDoc setObject:@"?????" forKey:@"devicename"];
    [mainDoc setObject:deviceType forKey:@"devicetype"];

    [mainDoc setObject:results forKey:@"test_results"];
    [mainDoc setObject:reports forKey:@"reports"];


    NSError *ierror = nil;
    NSData *jsnData = [NSJSONSerialization dataWithJSONObject:mainDoc options:NSJSONWritingPrettyPrinted error:&ierror];
    NSString *jsnString = [[NSString alloc] initWithData:jsnData encoding:NSUTF8StringEncoding];
    NSLog(@"JSON Output: %@", jsnString);


}

我的另一个担忧是 test_results 的输出也没有按照我想要的顺序出现。它们按“日期”、“名称”、“结果”的顺序出现，我希望输出为“名称”、“日期”、“结果”。有没有办法可以纠正这个订单？

NSDictionary 不提供有序存储容器 - 您可能应该首先研究如何呈现数据，即直接查询字典键以便对 NSDictionary 进行排序，以及将字典对象加载到 NSArray 中。

有大量关于 NSDictionary 固有的缺乏“顺序”的信息。

这个SO问题提供了许多有用的解决方案，例如使用具有有序字典类的外部库，以及使用SortDescriptors：Objective-C字典是一个有序的容器吗？ https://stackoverflow.com/questions/1648059/is-the-objective-c-dictionary-an-ordered-container