swift - 如何在不同情况下快速启用按钮？

Question

我想在不同情况下禁用和启用按钮:

如果用户来到我的共享 viewController 按钮将被禁用:

func handleShareAndAbortButton() {
    shareButton.isEnabled = false
    abortButton.isEnabled = false

    let attributedShareButtonText = NSAttributedString(string: shareButton.currentTitle!, attributes: [NSAttributedString.Key.foregroundColor: UIColor(red: 0, green: 0, blue: 0, alpha: 0.2) ])
    let attributedabortButtonText = NSAttributedString(string: abortButton.currentTitle!, attributes: [NSAttributedString.Key.foregroundColor: UIColor(red: 0, green: 0, blue: 0, alpha: 0.2) ])
    shareButton.setAttributedTitle(attributedShareButtonText, for: .normal)
    abortButton.setAttributedTitle(attributedabortButtonText, for: .normal)
}

handleShareAndAbortButton 将在 viewDidLoad 中调用

如果有什么改变(图片或文字)我想启用按钮:

func imageDidChange() {
    selectedText = postTextView.text!

    let isText = selectedText
    let isImage = selectedImage != nil

    if isImage || isText != "Schreibe etwas..." && isText != nil {
    shareButton.isEnabled = true
    abortButton.isEnabled = true

    let attributedShareButtonText = NSAttributedString(string: shareButton.currentTitle!, attributes: [NSAttributedString.Key.foregroundColor: UIColor(red: 255, green: 255, blue: 255, alpha: 1.0) ])
    let attributedabortButtonText = NSAttributedString(string: abortButton.currentTitle!, attributes: [NSAttributedString.Key.foregroundColor: UIColor(red: 0, green: 0, blue: 0, alpha: 1.0) ])
    shareButton.setAttributedTitle(attributedShareButtonText, for: .normal)
    abortButton.setAttributedTitle(attributedabortButtonText, for: .normal)
    }
}

我在 viewWillAppear 中调用了 imageDidChange

这里我在开始编辑后删除了占位符:

   extension ShareViewController: UITextViewDelegate {

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

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

当用户现在输入一些文本时，占位符“Schreibe etwas...”将消失，文本也将是 != nil。但它不起作用。

更新

我发现了问题。当我删除 isText != "Schreibe etwas..."有用。但我需要这个。我如何与字符串进行比较？如果我没有此代码，用户可以始终使用占位符文本上传。

预先感谢您的帮助!

Answer 1

您永远不会在更改文本后调用 imageDidChange。

使用:

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

     imageDidChange()
}