Question

我有一个UITextView，用户可以在textView中写入最多160个字符。如何修复UITextView的最大文本长度？

Answer 1

这段代码也适用于复制/粘贴，但在尝试粘贴将使文本视图超出限制的字符数时也能应对这种情况。在这种情况下，只粘贴字符串的第一个字符。

#define MAX_LENGTH 15 // Whatever your limit is
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSUInteger newLength = (textView.text.length - range.length) + text.length;
    if(newLength <= MAX_LENGTH)
    {
        return YES;
    } else {
        NSUInteger emptySpace = MAX_LENGTH - (textView.text.length - range.length);
        textView.text = [[[textView.text substringToIndex:range.location] 
                                            stringByAppendingString:[text substringToIndex:emptySpace]]
                                         stringByAppendingString:[textView.text substringFromIndex:(range.location + range.length)]];
        return NO;
    }
}

Answer 2

替换

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

与

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

已回答here

Answer 3

迟到这个答案; manicaesar的解决方案对我不起作用。这是我对同一想法的实现：

#define MAX_LENGTH 140
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)replacementText
{
    NSString *newText = [ textView.text stringByReplacingCharactersInRange: range withString: replacementText ];
    if( [newText length]<= MAX_LENGTH ){
        return YES;
    }
    // case where text length > MAX_LENGTH
    textView.text = [ newText substringToIndex: MAX_LENGTH ];
    return NO;
}

Answer 4

Swift 4，

我在swift 4中编写了UITextView的扩展，以使代码可重用。复制粘贴也可以正常工作。

    private var maxLengths = [UITextView: Int]()

extension UITextView : UITextViewDelegate {

  @IBInspectable var maxLength: Int {

    get {

      guard let length = maxLengths[self]
        else {
          return Int.max
      }
      return length
    }
    set {
      maxLengths[self] = newValue
      self.delegate = self
    }
  }

  @objc func limitLength(textView: UITextView) {
    guard let prospectiveText = textView.text,
      prospectiveText.count > maxLength
      else {
        return
    }

    let selection = selectedTextRange
    let maxCharIndex = prospectiveText.index(prospectiveText.startIndex, offsetBy: maxLength)
    text = String(prospectiveText[..<maxCharIndex])
    selectedTextRange = selection

  }

  public func textViewDidChange(_ textView: UITextView) {
    limitLength(textField:textView)
  }

  public func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    scrollToBottom()
    return true
  }

  public func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
    scrollToBottom()
    return true
  }

  func scrollToBottom() {
    let location = text.count - 1
    let bottom = NSMakeRange(location, 1)
    self.scrollRangeToVisible(bottom)
  }

}

在故事板中设置最大长度值

Answer 5

Swift 3

fileprivate let maxLen = 5

    extension MyViewController : UITextViewDelegate{
        func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

            let newLen = (textView.text.characters.count - range.length) + text.characters.count
            return newLen <= maxLen
        }

    }

如何修复UITextView的文本长度？

5 个答案: