数字字符串加入逗号位数分隔

-(NSString *)countNumAndChangeformat:(NSString *)num

{

int count = 0;

long long int a = num.longLongValue;

while (a != 0) {

count++;

a /= 10;    }

NSMutableString *string = [NSMutableString stringWithString:num];

NSMutableString *newstring = [NSMutableString string];

while (count > 3) {

count -= 3;

NSRange rang = NSMakeRange(string.length - 3, 3);

NSString *str = [string substringWithRange:rang];

[newstring insertString:str atIndex:0];

[newstring insertString:@"," atIndex:0];

[string deleteCharactersInRange:rang];

}

[newstring insertString:string atIndex:0];

return newstring;

}