输入框TextField首位禁止输入0或.-优快云博客

本文介绍了一个iOS应用程序中针对数字输入的验证方法，确保用户只能输入合法的数字格式，并且限制了小数点的数量和位置。该方法使用Objective-C编写，通过UITextField代理方法实现了对输入的实时监控。

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

{

    if ([textField.text rangeOfString:@"."].location == NSNotFound)
    {
        isHaveDian = NO;
    }
    if ([string length] > 0)
    {
        unichar single = [string characterAtIndex:0];//当前输入的字符
        if ((single >= '0' && single <= '9') || single == '.')//数据格式正确
        {
            //首字母不能为0和小数点
            if([textField.text length] == 0)
            {

                if(single == '.')
                {

                    [self showMyMessage:@"亲，第一个数字不能为小数点!"];

                    [textField.text stringByReplacingCharactersInRange:range withString:@""];

                    return NO;

                }

                if (single == '0')
                {

                    [self showMyMessage:@"亲，第一个数字不能为0!"];

                    [textField.text stringByReplacingCharactersInRange:range withString:@""];

                    return NO;

                }

            }

            //输入的字符是否是小数点

            if (single == '.')
            {

                if(!isHaveDian)//text中还没有小数点
                {

                    isHaveDian = YES;

                    return YES;

                }else{

                    [self showMyMessage:@"亲，您已经输入过小数点了!"];

                    [textField.text stringByReplacingCharactersInRange:range withString:@""];

                    return NO;

                }

            }else{

                if (isHaveDian) {//存在小数点

                    //判断小数点的位数

                    NSRange ran = [textField.text rangeOfString:@"."];

                    if (range.location - ran.location <= 2) {

                        return YES;

                    }else{

                        [self showMyMessage:@"亲，您最多输入两位小数!"];

                        return NO;

                    }

                }else{

                    return YES;

                }

            }

        }else{//输入的数据格式不正确

            [self showMyMessage:@"亲，您输入的格式不正确!"];

            [textField.text stringByReplacingCharactersInRange:range withString:@""];

            return NO;

        }

    }

    else

    {

        return YES;

    }

}

-(void)showMyMessage:(NSString*)aInfo {

    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"提示" message:aInfo delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];

    [alertView show];

}