ios - Swift - 无法在 UITextField 中从用户自定义光标位置

Question

我有一个文本字段，但我不希望用户能够通过触摸并按住文本字段来设置光标位置。有没有办法让光标始终位于文本字段的最后？

Answer 1

首先，改变textField的这种默认行为是不好的。

根据您的评论，如果您想添加信用卡并且面临一些输入复杂性，那么我从我的旧项目中找到了代码，可能它会为您工作。

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

            let replacementStringIsLegal = string.rangeOfCharacter(from: NSCharacterSet(charactersIn: "0123456789").inverted) == nil

            if !replacementStringIsLegal {
                return false
            }

            let newString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
            let components = newString.components(separatedBy: NSCharacterSet(charactersIn: "0123456789").inverted)

            let decimalString = components.joined(separator: "") as NSString
            let length = decimalString.length
            let hasLeadingOne = length > 0 && decimalString.character(at: 0) == (1 as unichar)

            if length == 0 || (length > 16 && !hasLeadingOne) || length > 19
            {
                let newLength = (textField.text! as NSString).length + (string as NSString).length - range.length as Int

                return (newLength > 16) ? false : true
            }
            var index = 0 as Int
            let formattedString = NSMutableString()

            if hasLeadingOne
            {
                formattedString.append("1 ")
                index += 1
            }
            if length - index > 4
            {
                let prefix = decimalString.substring(with: NSMakeRange(index, 4))
                formattedString.appendFormat("%@ ", prefix)
                index += 4
            }

            if length - index > 4
            {
                let prefix = decimalString.substring(with: NSMakeRange(index, 4))
                formattedString.appendFormat("%@ ", prefix)
                index += 4
            }
            if length - index > 4
            {
                let prefix = decimalString.substring(with: NSMakeRange(index, 4))
                formattedString.appendFormat("%@ ", prefix)
                index += 4
            }


            let remainder = decimalString.substring(from: index)
            formattedString.append(remainder)
            textField.text = formattedString as String
            return false     
    }