将400电话中间加上-线

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
     NSLog(@"--iphone--%@",[self getNewPhoneStr1:@"18502368888"]);
    
}
#pragma -mark -functions
//只需传一个电话进去，可以返回一个处理好的加了-线的400电话字符串，如传4001234567，返回400-123-4567
- (NSString *)getNewPhoneStr1:(NSString *)phonestr
{
    if ([phonestr rangeOfString:@"-"].length == 0 && phonestr.length > 6) {
        NSMutableString *phoneNumber = [NSMutableString string];
        NSString *subStr = [phonestr substringToIndex:3];
        [phoneNumber appendFormat:@"%@-",subStr];
        subStr = [phonestr substringWithRange:NSMakeRange(3, 3)];
        [phoneNumber appendFormat:@"%@-",subStr];
        subStr = [phonestr substringWithRange:NSMakeRange(6, phonestr.length-6)];
        [phoneNumber appendString:subStr];
        
        phonestr = phoneNumber;
    }
    
    return phonestr;
}