- (void)viewDidLoad

{

    [super viewDidLoad];

    // Do any additional setup after loading the view.

    //电话号码

    UILabel *telLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 100, 200, 20)];

    telLabel.textColor = [UIColor grayColor];

    telLabel.text = @"13793333281";

    //字符串的截取

    NSString *string = [telLabel.text substringWithRange:NSMakeRange(4,4)];

    //字符串的替换

    telLabel.text = [telLabel.text stringByReplacingOccurrencesOfString:string withString:@"----"];

    [self.view addSubview:telLabel];

}