Swift NSTextField 文本消失

这个问题可能存在于 Objective-c 的一篇 6 年前的帖子中。我还没有找到最近有效的答案或问题，或者是用 Swift 编写的答案或问题。

我正在使用故事板并且我已经子类化NSTextField。由于某种原因，当我单击该字段时，占位符会显示，当我输入文本并单击时，文本会消失。文本实际上在那里，因为当我单击返回时，输入的文本仍然存在。图层覆盖文本值似乎是某种类型的渲染问题？很奇怪。我在用着NSTrackingArea并且还添加CALayer.

Here's a screenshot of what happens:

这是我的代码：

class NowTextField: NSTextField {

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)

        // required nonsense
        let textFieldLayer = CALayer()
        let textFieldRect = NSRect(x: 0, y: 0, width: 120, height: 32)
        let textFieldTrackingArea = NSTrackingArea.init(rect: textFieldRect, options: [NSTrackingAreaOptions.activeInActiveApp, NSTrackingAreaOptions.mouseEnteredAndExited], owner: self, userInfo: nil)
        self.wantsLayer = true
        self.layer = textFieldLayer
        self.addTrackingArea(textFieldTrackingArea)

        // styling
        self.textColor = NSColor.darkGray
        self.layer?.cornerRadius = 4
        self.layer?.backgroundColor = NSColor.white.cgColor
        self.layer?.borderColor = NSColor.lightGray.cgColor
        self.layer?.borderWidth = 2
        self.drawsBackground = false
    }

    override func mouseEntered(with event: NSEvent) {
        self.textColor = NSColor.darkGray
        self.layer?.cornerRadius = 4
        self.layer?.backgroundColor = NSColor.white.cgColor
        self.layer?.borderColor = NSColor.highlightBlue.cgColor
        self.layer?.borderWidth = 2
        self.drawsBackground = false
    }

    override func mouseExited(with event: NSEvent) {
        self.textColor = NSColor.darkGray
        self.layer?.cornerRadius = 4
        self.layer?.backgroundColor = NSColor.white.cgColor
        self.layer?.borderColor = NSColor.lightGray.cgColor
        self.layer?.borderWidth = 2
        self.drawsBackground = false
    }
}

我找到了答案。我删掉了let textFieldLayer = CALayer()也self.layer = textFieldLayer因为这些似乎在文本字段的顶部添加了不必要的层。这是我的工作版本的完整代码：

class NowTextField: NSTextField {

override func draw(_ dirtyRect: NSRect) {
    super.draw(dirtyRect)

    // required nonsense
    let textFieldRect = NSRect(x: 0, y: 0, width: 120, height: 32)
    let textFieldTrackingArea = NSTrackingArea.init(rect: textFieldRect, options: [NSTrackingAreaOptions.activeInActiveApp, NSTrackingAreaOptions.mouseEnteredAndExited], owner: self, userInfo: nil)
    self.wantsLayer = true
    self.addTrackingArea(textFieldTrackingArea)

    // styling
    self.textColor = NSColor.darkGray
    self.layer?.cornerRadius = 4
    self.layer?.backgroundColor = NSColor.white.cgColor
    self.layer?.borderColor = NSColor.lightGray.cgColor
    self.layer?.borderWidth = 2
    self.drawsBackground = false
}

override func mouseEntered(with event: NSEvent) {
    self.textColor = NSColor.darkGray
    self.layer?.cornerRadius = 4
    self.layer?.backgroundColor = NSColor.white.cgColor
    self.layer?.borderColor = NSColor.highlightBlue.cgColor
    self.layer?.borderWidth = 2
    self.drawsBackground = false
}

override func mouseExited(with event: NSEvent) {
    self.textColor = NSColor.darkGray
    self.layer?.cornerRadius = 4
    self.layer?.backgroundColor = NSColor.white.cgColor
    self.layer?.borderColor = NSColor.lightGray.cgColor
    self.layer?.borderWidth = 2
    self.drawsBackground = false
}

}