IOS UITextView 和 UITextField 联想输入法字数限制

最新推荐文章于 2020-01-04 17:53:31 发布

原创最新推荐文章于 2020-01-04 17:53:31 发布 · 2.1k 阅读

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本文介绍了如何在iOS应用中为UITextField和UITextView设置输入字符长度限制。通过实现UITextFieldDelegate和UITextViewDelegate的方法，可以有效地控制用户输入的文本长度不超过预设的最大值。

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UITextField 输入限制

[_tfTextFeild addTarget:self action:@selector(limitLength:) forControlEvents:UIControlEventEditingChanged];

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField == _tfTextFeild)
    {
        if (string.length == 0) return YES;
        
        NSInteger existedLength = textField.text.length;
        NSInteger selectedLength = range.length;
        NSInteger replaceLength = string.length;
        if (existedLength - selectedLength + replaceLength > TEXT_MAXLENGTH)
        {
            return NO;
        }
    }
    
    return YES;
}

- (void)limitLength:(UITextField *)textField
{
    if (textField == _tfTextFeild)
    {
        if (textField.text.length > TEXT_MAXLENGTH)
        {
            textField.text = [textField.text substringToIndex:TEXT_MAXLENGTH];
        }
    }
}

UITextView输入限制

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewEditChanged) name:UITextViewTextDidChangeNotification object:nil];

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    if (textView == _contentTextView)
    {
        if (text.length == 0) return YES;
        
        NSInteger existedLength = textView.text.length;
        NSInteger selectedLength = range.length;
        NSInteger replaceLength = text.length;
        if (existedLength - selectedLength + replaceLength > TEXT_MAXLENGTH)
        {
            return NO;
        }
    }
    
    return YES;
}

- (void)textViewEditChanged
{
    if (_contentTextView.text.length > TEXT_MAXLENGTH)
    {
       _contentTextView.text = [_contentTextView.text substringToIndex:TEXT_MAXLENGTH];
    }
}