ios - 在iOS中对整数的NSMutableDictionary进行排序

Question

我只是想知道是否可以在 iOS 中对整数字典进行排序？查看前面的示例/问题，似乎大多数人都在对整数数组或字典数组（包含整数）进行排序。

但是，假设我有一本结构如下的字典：

 {numWords = 12, numPhotos = 15, numFriends = 8}

键不一样，所以似乎我不能使用排序描述符（用键初始化），所以有没有办法对整数进行排序并保持关联的键完好无损？

Answer 1

Dictionaries can't be sorted. But there is a method that will return an array of keys in order based on the values being sorted.

NSMutableDictionary *dict = ...; // your dictionary
NSArray *orderedKeys = [dict keysSortedByValueUsingSelector:@selector(compare:)];

In your case, orderedKeys would be numFriends, numWords, numPhotos.

To make use of the ordered keys you can do something like:

for (id key in orderedKeys) {
    id value = [dict objectForKey:key];
}

Answer 2

NSDictionary are not ordered. And you never sort dictionary.

Indeed you sort keys and or values.

For your case:

You need to extract all the values into arrayValues parallely keys in arraykeys, sort based on arrayValues.

NSMutableArray *array1 = [NSMutableArray arrayWithObjects:[NSNumber numberWithInt:5], [NSNumber numberWithInt:3], [NSNumber numberWithInt:1], [NSNumber numberWithInt:2], [NSNumber numberWithInt:4], [NSNumber numberWithInt:6], nil];
NSMutableArray *arrayKeys = @[@"Five", @"Three", @"One", @"Two", @"Four", @"Six"];
NSMutableArray *arrayValues = @[@"Cinq", @"Trois", @"Un", @"Deux", @"Quatre", @"Six"];
 [array1 sortArrayUsingSelector:@selector(compare:) withPairedMutableArrays:arrayKeys, arrayValues, nil];

After the call to sortArrayUsingSelector:withPairedArrays:, the three arrays will all be in numeric order, so arrayKeys will look like this:

One, Two, Three, Four, Five, Six

and arrayValues will look like this:

Un, Deux, Trois, Quatre, Cinq, Six

Answer 3

字典不可排序。

也就是说，您可以有两个排序数组，一个包含键，另一个包含关联的值。按值的顺序对它们进行排序。

NSDictionary *d = @{
    @"numWords": @12,
    @"numPhotos": @15,
    @"numFriends": @8
};

NSComparisonResult (^cmp)(id, id) = ^(id obj1, id obj2) {
    return [obj1 compare:obj2];
}

NSArray *keys = [d keysSortedByValueUsingComparator:cmp]
NSMutableArray *vals = [[id allValues] mutableCopy];
[vals sortUsingComparator:cmp];

Answer 4

假设对象是唯一的：

1) 向字典查询allValues的数组

2）对值数组进行排序

3）由于没有valueForKey，对于每个值，使用快速枚举或enumerateKeysAndObjectsUsingBlock:来找到合适的键。