NSDictionary按键排序为浮点数 [英] NSDictionary sort by keys as floats

问题描述

基本上我有一个带有键和值的NSDictionary。

basically I have an NSDictionary with keys and values.

键都是数字，但目前它们是字符串。

The keys are all numbers, but at the moment they are strings.

我希望能够将它们作为数字进行比较以便对它们进行排序。

I want to be able to compare them as numbers in order to sort them.

例如：如果我有这样的字典：

eg: If I have a Dictionary like this:

{
  "100"  => (id)object,
  "20"   => (id)object,
  "10"   => (id)object,
  "1000" => (id)object,
}

我希望能够像这样排序：

I want to be able to sort it like this:

{
  "10"   => (id)object,
  "20"   => (id)object,
  "100"  => (id)object,
  "1000" => (id)object,
}

任何想法？

谢谢

Tom

推荐答案

不确定你要做什么 - 词典本质上是未排序的，默认实现中没有稳定的键排序。如果你想按排序键遍历值，你可以这样做：

Not sure what you are up to – dictionaries are inherently unsorted, there is no stable key ordering in the default implementation. If you want to walk the values by sorted keys, you can do something like this:

NSInteger floatSort(id num1, id num2, void *context)
{
    float v1 = [num1 floatValue];
    float v2 = [num2 floatValue];
    if (v1 < v2)
        return NSOrderedAscending;
    else if (v1 > v2)
        return NSOrderedDescending;
    else
        return NSOrderedSame;
}

NSArray *allKeys = [aDictionary allKeys];
NSArray *sortedKeys = [allKeys sortedArrayUsingFunction:floatSort context:NULL];
for (id key in sortedKeys)
    id val = [aDictionary objectForKey:key];
    …

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