替换电话号码中间4位为-号

//电话号码

    UILabel*telLabel = [[UILabelalloc] initWithFrame:CGRectMake(10, yy+30,200,20)];

    telLabel.textColor= [UIColor grayColor];

    telLabel.text= @"13793333281";

    //字符串的截取

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

    //字符串的替换

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

    [self.viewaddSubview:telLabel];