为什么json值按字母顺序iOS排序？

Question

可能重复：

JSONkit sorting issues

我有下面的jSON

[
  {
    "Pending": 67,
    "Past Due": 63,
    "Invites": 0
  },
  {
    "Reading Approval": 4,
    "Schedule Approval": 16,
    "Session Assignment": 1
  },
  {
    "Reading Approval": 3,
    "Schedule Approval": 20,
    "Class Approval": 20,
    "Module Approval": 2,
    "Training Plan Review": 2,
    "Job Confirmation": 1
  }

]

当我将json字符串分配给nsarray时，字典中的值会按字母顺序排序。

NSArray *arr = [strResult JSONValue]; 

如何保持与json字符串相同的顺序？

arr = 
{
  Invites = 0;
  "Past Due" = 63;
  Pending = 67;
},
{
  "Reading Approval" = 4;
  "Schedule Approval" = 16;
  "Session Assignment" = 1;
},
{
  "Class Approval" = 20;
  "Job Confirmation" = 1;
  "Module Approval" = 2;
  "Reading Approval" = 3;
  "Schedule Approval" = 20;
  "Training Plan Review" = 2;
}
)

这是我想显示的表：

Group 1
  Pending    67
  Past Due   63
  Invites    0

Group 2
  Reading Approval    4
  Schedule Approval   16
  Session Assignment  1

Group 3
  Reading Approval      3
  Schedule Approval     20
  Class Approval        20
  Module Approval       2
  Training Plan Review  2
  Job Confirmation      1

Answer 1

使用标准的JSON解析器，您将需要更改数据。

[
  [
    { "Pending": 67 },
    { "Past Due": 63 },
    { "Invites": 0 }
  ],
  [
    { "Reading Approval": 4 },
    { "Schedule Approval": 16 },
    { "Session Assignment": 1 }
  ],
  [
    { "Reading Approval": 3 },
    { "Schedule Approval": 20 },
    { "Class Approval": 20 },
    { "Module Approval": 2 },
    { "Training Plan Review": 2 },
    { "Job Confirmation": 1 }
  ]
]

假设您可以更改JSON格式。

如何访问数据。假设您有一个节数组，并且知道节和行索引。

NSArray *sections = ...
NSUInteger sectionIndex = ...
NSUInteger rowIndex = ...

NSArray *rows = [sections objectAtIndex:sectionIndex];
NSDictionary *cell = [rows objectAtIndex:rowIndex];

NSString *name = [[cell allKeys] objectAtIndex:0];
NSNumber *value = [cell objectForKey:name];

// What ever you need to do

如果您想迭代所有的数据

NSArray *sections = ...

for (NSArray *rows in sections) {
    for (NSDictionary *cell in rows) {
        NSString *name = [[cell allKeys] objectAtIndex:0];
        NSNumber *value = [cell objectForKey:name];

        // What ever you need to do
    }
}

Answer 2

NSDictionary是无序容器对象。如果它被打印出来，它将按字母顺序排序。但是没有保证的秩序。

description:的文档显示：

If each key in the dictionary is an NSString object, the entries are listed in ascending order by key, otherwise the order in which the entries are listed is undefined. [...]

allKeys:说：

The order of the elements in the array is not defined.

allValues还说：

The order of the elements in the array is not defined.

但是NSArray是一个命令的容器。这就是Jeffery Thomas statet的原因，您应该为每个JSON条目使用数组。

但你也可以试着用这样的气味：

[
  [
    "keys": {"Pending","Past Due","Invites"},
    "values": {67,63,0}
  ],
  [
    "keys": {"Reading Approval","Schedule Approval","Session Assignment"},
    "values": {4,16,1},
  ],
  [
    "keys": {"Reading Approval","Schedule Approval","Class Approval",...},
    "values": {3,20,20,...},
  ]
]

Answer 3

字典中的项目没有排序。排序是由iOS完成的，只是为了很好地显示它。但是，您不应该假设字典中的项目排序。