Objective-C：根据字典条目对NSDictionary的键进行排序 [英] Objective-C: Sort keys of NSDictionary based on dictionary entries

问题描述

好的，所以我知道字典无法排序。但是，假设我有 NSMutableArray * keys = [someDictionary allKeys]; 现在，我想根据字典中的对应值（按字母顺序）对这些键进行排序。因此，如果字典包含 key = someString ，那么我想根据它们对应的字符串对键进行排序。我认为它是 sortUsingComparator 的某些应用程序，但是在这一点上，我觉得有点超出我的能力。

OK so I know that dictionaries can't be sorted. But, say I have NSMutableArray *keys = [someDictionary allKeys]; Now, I want to sort those keys, based on the corresponding values in the dictionary (alphabetically). So if the dictionary contains key=someString, then I want to sort keys based on the strings they correspond to. I think its some application of sortUsingComparator but its a little out of my reach at this point.

推荐答案

NSArray *keys = [someDictionary allKeys];
NSArray *sortedKeys = [keys sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSString *first = [someDictionary objectForKey:a];
    NSString *second = [someDictionary objectForKey:b];
    return [first compare:second];
}];

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