OC中的精简冒泡排序

NSArray *arr = @[@"9", @"-8", @"0", @"5"];

        //arr = [arr sortedArrayUsingSelector:@selector(compare:)];//升序

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

            return -[obj1 compare:obj2];

        }];//降序

        NSLog(@"%@", arr);