Question

我在UITextView上使用 shouldChangeTextIn ，并且可以使用 shouldChangeTextIn 中的以下代码将TextView限制为最多4行或最多140个字符>：

最多4行：

    let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
    let newLines = text.components(separatedBy: CharacterSet.newlines)
    let linesAfterChange = existingLines.count + newLines.count - 1

    return linesAfterChange <= textView.textContainer.maximumNumberOfLines

最多140个字符：

    let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)

    return newText.utf16.count < 140

但是，我想将两者结合起来，以便对它们进行检查，而我无法弄清楚。谁能指导我正确的方向？

最好的问候，埃里克

Answer 1

您应该存储布尔值而不是返回布尔值，并将其与&&组合并返回。

let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
let newLines = text.components(separatedBy: CharacterSet.newlines)
let linesAfterChange = existingLines.count + newLines.count - 1
let linesCheck = linesAfterChange <= textView.textContainer.maximumNumberOfLines

let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)
let characterCountCheck = newText.utf16.count < 140

return linesCheck && characterCountCheck

侧注：：避免在Swift中使用NSString。您可以使用String做同样的事情。

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if let textViewString = textView.text, let range = Range(range, in: textViewString) {
        let newString = textViewString.replacingCharacters(in: range, with: text)
    }
    return condition
}

Answer 2

使用&&（和运算符）组合布尔值并返回结果

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

        let existingLines = textView.text.components(separatedBy: CharacterSet.newlines)
        let newLines = text.components(separatedBy: CharacterSet.newlines)
        let linesAfterChange = existingLines.count + newLines.count - 1

        let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)

        return linesAfterChange <= textView.textContainer.maximumNumberOfLines && newText.utf16.count < 140
    }

UITextView中最多4行和总共140个字符

2 个答案: