Question

我正在尝试创建如下所示的JSON：

{
  "id": "feed/http://feeds.feedburner.com/design-milk",
  "title": "Design Milk",
  "categories": [
    {
      "id": "user/category/test",
      "label": "test"
    }
  ]
}

我正在使用这种方法：

NSMutableDictionary *req = [NSMutableDictionary @"feed/http://feeds.feedburner.com/design-milk" forKey:@"id"];
[req @"Design Milk" forKey:@"title"];

NSDictionary *tmp = [[NSDictionary alloc] initWithObjectsAndKeys:
                     @"user/category/test", @"id", @"test", @"label",
                     nil];

[req setObject:tmp forKey:@"categories"];

NSData *postdata = [NSJSONSerialization dataWithJSONObject:req options:0 error:&error];

但是，这不起作用。我在这里做错了什么？

Answer 1

您的代码的第一行不会编译，因此您需要修复它。

＆＃34;类别＆＃34;的价值在您的示例输出中是一个包含一个元素的数组，它恰好是一个字典。所以你需要

NSDictionary* oneCategory = [NSDictionary dictionaryWithObjectsAndKeys:...];
NSArray* categories = [NSArray arrayWithObject:oneCategory];
[req setObject:categories forKey:@"categories"];

你应该使用更现代的语法，比如

req [@"categories"] = @[oneCategory];

Answer 2

你错过了一个数组：

NSMutableDictionary *req =[NSMutableDictionary  dictionaryWithObjectsAndKeys:@"feed/http://feeds.feedburner.com/design-milk", @"id", nil];
req[@"title"] = @"Design Milk";
NSDictionary *tmp = [[NSDictionary alloc] initWithObjectsAndKeys:
                     @"user/category/test", @"id",
                     @"test", @"label",
                     nil];
NSMutableArray *arr = [[NSMutableArray alloc] init];
[arr addObject:tmp];
[req setObject:arr forKey:@"categories"];
NSError *error;
NSData *postdata = [NSJSONSerialization dataWithJSONObject:req options:0 error:&error];

在Objective-C中创建嵌套的JSON

2 个答案: