Swift NSTextField 文本消失答案

【问题标题】：Swift NSTextField text disappearsSwift NSTextField 文本消失
【发布时间】：2017-06-06 17:35:03
【问题描述】：

这个问题可能存在于 Objective-c 中一个 6 年前的帖子中。我没有找到最近的答案或问题，或者用 Swift 编写的。

我正在使用情节提要，并且已将 NSTextField 子类化。出于某种原因，当我单击该字段时，会显示占位符，当我输入文本并单击退出时，文本会消失。文本实际上在那里，因为当我重新点击时，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。我正在使用NSTrackingArea 并添加CALayer。

这是发生的情况的屏幕截图：

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
    }
}

【问题讨论】：

在 init 方法或 awakeFromNib() 中设置文本字段，而不是在每个 draw 中设置。
不幸的是，这并没有解决问题。添加到awakeFromNib()时一切都一样

标签： swift macos nstextfield nstrackingarea

【解决方案1】：

我找到了答案。我删除了let textFieldLayer = CALayer() 和self.layer = textFieldLayer，因为它们似乎在文本字段的顶部添加了不必要的层。这是我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
}

}

【讨论】：