NSMutableArray *array = [NSMutableArray arrayWithObjects:@"12",@"84", @"35", @"70", @"85", @"99", nil];

        NSInteger count = [array count];

        for (int i = 0; i < count; i++) {

            for (int j = 0; j < count - i - 1; j++) {

               // if ([[array objectAtIndex:j] intValue] > [[array objectAtIndex:(j + 1)] intValue]) {   //这里在用[array objectAtIndex:j]时候必须intValue

//                if([[array objectAtIndex:j] compare:[array objectAtIndex:j + 1]] == -1){  //这里整体必须有一个返回值，－1，0，1，因为compare的返回值NSComparisonResult是一个枚举类型的值，所以要返回一个值

                if([[array objectAtIndex:j] compare:[array objectAtIndex:j + 1] options:NSNumericSearch] == 1){  //同上potions  NSNumericSearch = 64,

                    [array exchangeObjectAtIndex:j withObjectAtIndex:(j + 1)];  //这里可以用exchangeObjectAtIndex:方法来交换两个位置的数组元素。

                }

            }

        }

        for (NSString *i in array) {

            NSLog(@"%@", i);

        }

        NSMutableArray *array1 = [NSMutableArray arrayWithObjects:@"12",@"84", @"35", @"70", @"85", @"99", nil];

        [array1 sortUsingSelector:@selector(compare:)];

        NSLog(@"%@", array);