iphone - Textview 倒计时标签

Question

我正在尝试对我的文本视图进行倒计时。我的 .h 和 .m 文件设置如下。基本上，我正在寻找的只是一个 textview 一个标签，当用户输入文本时，它会从 140 开始倒计时。一旦 textview 达到 140 个字符，用户将无法再输入文本。我不确定我在这里做错了什么。任何帮助都会很棒！谢谢！

在我的 .h 文件中：

@interface LeaveTipViewController : UIViewController

@property (weak, nonatomic) IBOutlet UIBarButtonItem *tipCancelButton;

@property (weak, nonatomic) IBOutlet UIBarButtonItem *tipSubmitButton;

@property (weak, nonatomic) IBOutlet UITextView *tipText;

@property (weak, nonatomic) IBOutlet UILabel *countLabel;

- (IBAction)tipCancelPressed:(id)sender;

- (IBAction)tipSubmitPressed:(id)sender;

@end

在我的 .m 文件中：

-(void)textViewDidChange:(UITextView *)textView
{
    int len = tipText.text.length;
    countLabel.text=[NSString stringWithFormat:@"%i",140-len];

}

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range 
replacementText:(NSString *)text
{
    BOOL flag = NO;
    if([text length] == 0)
    {
        if([tipText.text length] != 0)
        {
            flag = YES;
            return YES;
        }
        else {
            return NO;
        }
    }
    else if([[tipText text] length] > 139)
    {
        return NO;
    }
    return YES;
}

Answer 1

只需将您的此方法更改为

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    return textView.text.length + (text.length - range.length) <= 140;
}

Answer 2

在决定是否允许编辑之前，您需要计算编辑完成后可能存在的实际文本：

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSString *resultingText = [textView.text stringByReplacingCharactersInRange:range withString:text];

    return ([resultingText length] <= 140);
}

Answer 3

添加到您的 viewController 界面 LeaveTipViewController ： UIViewController

设置 self.tipText.delegate = self

并使用这两种方法

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range   replacementText:(NSString *)text
{
 NSUInteger newLength = [textView.text length] + [text length] - range.length;
 return (newLength > 140) ? NO : YES;
}

-(void)textViewDidChange:(UITextView *)textView
{
 int maxChars = 140;
 int charsLeft = maxChars - [textView.text length];

        if(charsLeft == 0) {
    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"No more characters"
                                                     message:[NSString stringWithFormat:@"You have reached the character limit of %d.",maxChars]
                                                    delegate:nil
                                           cancelButtonTitle:@"Ok"
                                           otherButtonTitles:nil];
    [alert show];
}

  self.lblLettersCount.text = [NSString stringWithFormat:@"%d characters left",charsLeft];
}

Answer 4

您可以使用以下代码检查并获取字符数：

- (void)textViewDidChange:(UITextView *)textView{

    NSInteger maxLength = 140;

    NSString *text = textView.text;

    if([[textView text] length] > maxLength )
    {
        textView.text = [text substringToIndex:[text length]-1];
    }
}