如何在Swift语言中更改NSView的转角半径 [英] How to change Corner Radius of NSView in Swift Language

问题描述

更改NSView的拐角半径应该很简单，但是我收到错误消息严重错误:无法解开Optional.None".我是否有可能用10.9而不是10.10进行此操作，这是由于框架差异而发生的吗?或代码错误.

changing corner radius of NSView should be pretty straight forward however i am getting error message "fatal error: Can't unwrap Optional.None". is there a chance i am doing this with 10.9 not 10.10 and this is happening due framework differences? or the code is wrong.

class aRoundView: NSView {

    let cornerRad = 5.0

    init(frame: NSRect) {
        super.init(frame: frame)

        self.layer.cornerRadius  = cornerRad
    }

    override func drawRect(dirtyRect: NSRect)
    {
        super.drawRect(dirtyRect)
        NSColor.redColor().setFill()
        NSRectFill(dirtyRect)
    }
}

编辑

用

func applicationDidFinishLaunching(aNotification: NSNotification?) {

    let aView = mainViewTest(frame: NSMakeRect(0, 0, 100, 100))
    self.window.contentView.addSubview(aView)

}

实际上，不仅如此.使用self.layer进行的任何迭代都会得到相同的结果，backgroundcolor等.

actually it is not just that. any iteration with self.layer gives same result, backgroundcolor etc.

推荐答案

这是因为self.layer是一个可选值，当前未设置.在self.layer.cornerRadius之前添加self.wantsLayer = true，以确保存在正确的layer.

That is because self.layer is an optional value, which is currently not set. Add self.wantsLayer = true before self.layer.cornerRadius, to make sure a proper layer exists.

init(frame: NSRect) {
    super.init(frame: frame)
    self.wantsLayer = true
    self.layer.cornerRadius  = cornerRad
}

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