数组包含字典-根据key排序

NSArray *array = [NSArray array];

    [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2){

        NSNumber index1 = [obj1 valueForKey:@"index"];

        NSNumber index2 = [obj2 valueForKey:@"index"];

        return [index1 compare:index2];

    }];