iOS 用objective

如：123456789

变为：123,456,789

直接上代码

1+(NSString *)countNumAndChangeformat:(NSString *)num
2{
3    int count = 0;
4    long long int a = num.longLongValue;
5    while (a != 0)
6    {
7        count++;
8        a /= 10;
9    }
10    NSMutableString *string = [NSMutableString stringWithString:num];
11    NSMutableString *newstring = [NSMutableString string];
12    while (count > 3) {
13        count -= 3;
14        NSRange rang = NSMakeRange(string.length - 3, 3);
15        NSString *str = [string substringWithRange:rang];
16        [newstring insertString:str atIndex:0];
17        [newstring insertString:@"," atIndex:0];
18        [string deleteCharactersInRange:rang];
19    }
20    [newstring insertString:string atIndex:0];
21    return newstring;
22}