设置 `UITextView ` 和 `UITextField ` 的最大字符数

Question

我想设置允许在 UITextView 和 UITextField 中输入的最大字符数。然后这个数字将显示在一个小标签中（供用户参考，Twitter 样式。）

Answer 1

更新Swift4.X

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)
    let numberOfChars = newText.count
    return numberOfChars < 10    // 10 Limit Value
}

试试这个：

func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    let newText = (textView.text as NSString).stringByReplacingCharactersInRange(range, withString: text)
    let numberOfChars = newText.characters.count // for Swift use count(newText)
    return numberOfChars < 10;
}

Answer 2

试试这个：-

 func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    print("chars \(textView.text.characters.count) \( text)")

    if(textView.text.characters.count > 20 && range.length == 0) {
        print("Please summarize in 20 characters or less")
        return false;
    }

    return true;
}

Answer 3

SWIFT 4

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
     let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)
     return newText.count < 10
}

Answer 4

Swift 3.0

只需覆盖此 UITextFieldDelegate 函数，设置所需的 characterLimit 变量即可：

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool 
{        
        let characterLimit = 5
        let newText = NSString(string: textField.text!).replacingCharacters(in: range, with: string)
        let numberOfChars = newText.characters.count
        return numberOfChars < characterLimit
}

Answer 5

Swift 4:

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
  let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)
  return newText.count <= 70
}

Answer 6

Swift 4 , Xcode 9.1 GM

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    return textView.text.count + (text.count - range.length) <= 200
}

Answer 7

Swift4/Xcode9.1

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

    let currentText = textView.text ?? ""
    guard let stringRange = Range(range, in: currentText) else { return false }
    let changedText = currentText.replacingCharacters(in: stringRange, with: text)
    return changedText.count <= 399 // Pass your character count here 
}

Answer 8

Swift 5

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    var newText = textView.text!
    newText.removeAll { (character) -> Bool in
        return character == " " || character == "\n"
    }

    return (newText.count + text.count) <= 40
}

Answer 9

添加通过 maxLength 剪切粘贴文本的支持 + 避免 UNDO 操作崩溃：

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if let maxLength = maxLength {
        let maxReplacementLength = min(range.length, maxLength - range.location)
        let replacementRange = NSRange(location: range.location, length: maxReplacementLength)
        let result = NSString(string: (textView.text ?? "")).replacingCharacters(in: replacementRange, with: text)
        
        if result.count <= maxLength && range.length <= maxLength - range.location  {
            return true
        }
        textView.text = String(result[..<result.index(result.startIndex, offsetBy: min(result.count, maxLength))])
        
        return false
    }
    
    return true
}

设置 `UITextView ` 和 `UITextField ` 的最大字符数

Setting maximum number of characters of `UITextView ` and `UITextField `

uitextfield

uitextview

ios

swift