NSArray排序

NSComparatorcmptr = ^(idobj1,idobj2) {

        int dicOne;
        int dicTwo;
        if ([[obj1 objectForKey:@"user_id"]isEqual:[NSNullnull]]) {
            dicOne = 0;
        }else{
            dicOne = [[obj1 objectForKey:@"user_id"]intValue];
        }
       
        if ([[obj2 objectForKey:@"user_id"]isEqual:[NSNullnull]]) {
            dicTwo = 0;
        }else{
            dicTwo = [[obj2 objectForKey:@"user_id"]intValue];
        }
       
        if (dicOne > dicTwo) {
           
            return (NSComparisonResult)NSOrderedDescending;
        }
        if (dicOne < dicTwo) {
            return (NSComparisonResult)NSOrderedAscending;
        }
        return (NSComparisonResult)NSOrderedSame;
       
    };

    tempArr = [tempArrsortedArrayUsingComparator:cmptr];

//以上是tempArr由大到小排序，其中user_id为object中的key,也就是根据user_id大小来排序。