UITextField限制字数的方法

来源：互联网发布：觉得做程序员越来越烦编辑：程序博客网时间：2024/04/30 07:59

参考博客：http://www.oschina.net/code/snippet_54100_8632

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;

{
    if ([string isEqualToString:@"\n"])
    {
        return YES;
    }
    NSString * toBeString = [textField.text stringByReplacingCharactersInRange:range withString:string]; //关键代码。将新输入的内容与原内容合并

    if (self.myTextField == textField)
    {
        if ([toBeString length] > 20) {
            textField.text = [toBeString substringToIndex:20]; //总内容超过限制字数20，则截取前20个字符
            UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:nil message:@"超过最大字数不能输入了" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil] autorelease];
            [alert show];
            return NO;
        }
    }
return YES;
}