如何在Swift中的UITextView中添加占位符文本？

为Swift 4更新

UITextView

UITextViewDelegate

注意：对于这两种解决方案，请添加

UITextViewDelegate

textView.delegate =self

解决方案＃1- 如果您希望占位符在用户选择文本视图后立即消失：

首先将设置

UITextView

UITextField

viewDidLoad

textView.text = "Placeholder"textView.textColor = UIColor.lightGray

然后，当用户开始编辑文本视图时，如果文本视图包含占位符（即，如果其文本颜色为浅灰色），则清除占位符文本并将文本颜色设置为黑色，以适应用户的输入。

func textViewDidBeginEditing(_ textView: UITextView) {    if textView.textColor == UIColor.lightGray {        textView.text = nil        textView.textColor = UIColor.black    }}

然后，当用户完成文本视图的编辑并将其辞去为第一响应者时，如果文本视图为空，请通过重新添加占位符文本并将其颜色设置为浅灰色来重置其占位符。

func textViewDidEndEditing(_ textView: UITextView) {    if textView.text.isEmpty {        textView.text = "Placeholder"        textView.textColor = UIColor.lightGray    }}

解决方案2- 如果希望占位符在文本视图为空时显示，即使选择了文本视图：

首先在中设置占位符

viewDidLoad

textView.text = "Placeholder"textView.textColor = UIColor.lightGraytextView.becomeFirstResponder()textView.selectedTextRange = textView.textRange(from: textView.beginningOfdocument, to: textView.beginningOfdocument)

（注意：由于OP希望在加载视图后立即选择文本视图，因此我将文本视图选择合并到了上面的代码中。如果这不是您想要的行为，并且您不希望在加载视图时选择文本视图，从上面的代码块中删除最后两行。）

然后利用该

shouldChangeTextInRange

UITextViewDelegate

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {    // Combine the textView text and the replacement text to    // create the updated text string    let currentText:String = textView.text    let updatedText = (currentText as NSString).replacingCharacters(in: range, with: text)    // If updated text view will be empty, add the placeholder    // and set the cursor to the beginning of the text view    if updatedText.isEmpty {        textView.text = "Placeholder"        textView.textColor = UIColor.lightGray        textView.selectedTextRange = textView.textRange(from: textView.beginningOfdocument, to: textView.beginningOfdocument)    }    // Else if the text view's placeholder is showing and the    // length of the replacement string is greater than 0, set     // the text color to black then set its text to the    // replacement string     else if textView.textColor == UIColor.lightGray && !text.isEmpty {        textView.textColor = UIColor.black        textView.text = text    }    // For every other case, the text should change with the usual    // behavior...    else {        return true    }    // ...otherwise return false since the updates have already    // been made    return false}

并且还实现

textViewDidChangeSelection

textViewDidChangeSelection

func textViewDidChangeSelection(_ textView: UITextView) {    if self.view.window != nil {        if textView.textColor == UIColor.lightGray { textView.selectedTextRange = textView.textRange(from: textView.beginningOfdocument, to: textView.beginningOfdocument)        }    }}