swift - UITextView 的占位符文本与 First Responder 混合

Question

我目前有一个带有占位符文本的 TextView ，每当用户点击 TextView 时，该 TextView 就会消失，并且如果 TextView 为空，则每当第一响应者辞职时， TextView 中的文本就会重新出现。 (这是我使用的代码，以防有人想使用它)

*注意，先将textview的文字颜色设置为浅灰色，并设置占位符文字。然后使用这些方法:

func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
    //If it begins editing, then set the color to black
    if (textView.tag == 0){
        textView.text = ""
        textView.textColor = .black
        textView.tag = 1
    }
    return true
}


func textViewDidEndEditing(_ textView: UITextView) {
    if textView.text.isEmpty {
        textView.text = "Example: I started my career as a street wear model based in Maryland. After 3 years of working with some of the top companies there, I moved to LA, where I currently reside. I’ve been featured in shows, 12 magazines, commercials, and a number of music videos. Now, Im currently looking to continue working with clothing companies and campaigns."
        textView.textColor = .lightGray
        textView.tag = 0
    }
}

我想更上一层楼。现在，只要 TextView 成为第一响应者，文本就会消失。 我希望文本在用户实际开始输入时消失，而不仅仅是在选择 TextView 时消失。当屏幕出现时，我自动将第一响应者设置为 TextView 并计划保留它那样。但是因为它是自动设置的，所以您看不到占位符文本。 我只希望 TextView 在用户按下某个键时消失，而不是因为它被选中。

Answer 1

假设您有这样的占位符文本，

let placeholderText = "Example: I started my career as a street wear model based in Maryland. After 3 years of working with some of the top companies there, I moved to LA, where I currently reside. I’ve been featured in shows, 12 magazines, commercials, and a number of music videos. Now, Im currently looking to continue working with clothing companies and campaigns."

并且在调用 的 becomeFirstResponder 之前，您在 storyboard 或 viewDidLoad 中将此文本设置为 textView > TextView 。

然后在这两个委托(delegate)方法中，您可以实现如下行为，

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    if textView.text == placeholderText {
        textView.text = ""
    }
    return true
}

func textViewDidEndEditing(_ textView: UITextView) {
    if textView.text.isEmpty {
        textView.text = placeholderText
    }
}

目前您正在清除 textViewShouldBeginEditing 中的文本，因此，这是您看不到该文本的主要原因。您应该删除清除那里的文本，但您可以按原样继续更改颜色等。