macos - How can I create a window with transparent background with swift on osx?

Question

I want to create an osx/cocoa application on my mac, which does something very simple: Display a text string on my mac, with no background. Ultimately this will be a timer which displays as an overlay on top of other windows, without being too intrusive.

I tried setting window.backgroundColor = NSColor(red: 1.0, green:0.5, blue:0.5, alpha: 0.5) (see the alpha is 0.5), in applicationDidFinishLaunching but this doesn't turn it into something remotely transparent.

Any good soul wants to suggest a way to do this?

Answer 1

NSWindow has a property 'opaque' which it is true by default.

The value of this property is true when the window is opaque; otherwise, false.

Just change it to false:

override func viewWillAppear() {
    super.viewWillAppear()
    view.window?.opaque = false
    view.window?.backgroundColor = NSColor(red: 1, green: 0.5, blue: 0.5, alpha: 0.5)
}

Swift 4 update: opaque has been renamed isOpaque

override func viewWillAppear() {
    super.viewWillAppear()
    view.window?.isOpaque = false
    view.window?.backgroundColor = NSColor(red: 1, green: 0.5, blue: 0.5, alpha: 0.5) 
}