A sorted helper

假设有个这样的Dictionary,叫numDic:

@{@"a" : @(1), @"b" : @(2), @"dd" : @(4), @"pp" : @(0)}

现在要对其每个key对应的value排序，也就是对1，2，3排序(假设升序), 结果应该是:

@[@"pp", @"a", @"b", @"dd"]

现在你需要的只是一个对象假设叫SortedHelper

- (id)initWithKey:(NSString *)skey withCount:(NSInteger)scount
{
    if (self = [super init]) {
        self.key = skey;
        self.count = scount;
    }
    return self;
}

- (NSComparisonResult)myCompare:(SortDictHelper *)helper
{
    return self.count >= helper.count ? NSOrderedAscending : NSOrderedDescending;
}

- (NSComparisonResult)yourCompare:(SortDictHelper *)helper;
{
    return self.count >= helper.count ? NSOrderedDescending : NSOrderedAscending;
}

+ (NSArray *)sortedDecending:(BOOL)decending mapDic:(NSDictionary *)dic
{
    NSMutableArray *mArray = [NSMutableArray arrayWithCapacity:dic.count];
    [dic enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        if ([obj isKindOfClass:[NSArray class]]) {
            NSArray *array = obj;
            SortDictHelper *helper = [[SortDictHelper alloc] initWithKey:key withCount:array.count];
            [mArray addObject:helper];
        }else if ([obj isKindOfClass:[NSNumber class]]){
            NSNumber *number = obj;
            SortDictHelper *helper = [[SortDictHelper alloc] initWithKey:key withCount:[number integerValue]];
            [mArray addObject:helper];
        }
    }];

    if(decending)
        [mArray sortUsingSelector:@selector(myCompare:)];
    else
        [mArray sortUsingSelector:@selector(yourCompare:)]

    NSMutableArray *keyArray = [NSMutableArray arrayWithCapacity:dic.count];
    [mArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        SortDictHelper *helper = obj;
        [keyArray addObject:helper.key];
    }];
    return keyArray;
}

使用就是:

NSArray *result = [SortedHelper sortedDecending:NO mapDic:numDic];

当然这里也对:

@{@"a" : @[@"cc", @"dd", @"ee"], @"b" : @[@"00", @"33"], @"pp" : @[@"1"]}

这种数据结构做了扩展。