How can I use NSVisualEffectView in window's title bar?

Question

In OS X Yosemite, Apple introduced a new class NSVisualEffectView. Currently, this class is undocumented, but we can use it in Interface Builder.

How can I use NSVisualEffectView in the window's title bar?

Here's example: in Safari, when you scroll, the content appears under the toolbar and titlebar with a vibrance and blur effect.

Answer 1

@sgonzalez's answer forced me to explore NSWindow.h file where i found titlebarAppearsTransparent property.

So we get:

class BluredWindow: NSWindow {

    override func awakeFromNib() {

    let visualEffectView = NSVisualEffectView(frame: NSMakeRect(0, 0, 300, 180))
    visualEffectView.material = NSVisualEffectView.Material.dark
    visualEffectView.blendingMode = NSVisualEffectView.BlendingMode.behindWindow
    visualEffectView.state = NSVisualEffectView.State.active

    self.styleMask = self.styleMask | NSFullSizeContentViewWindowMask
    self.titlebarAppearsTransparent = true
    //self.appearance = NSAppearance(named: NSAppearanceNameVibrantDark)



    self.contentView.addSubview(visualEffectView)

    self.contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[visualEffectView]-0-|", 
                                                                   options: NSLayoutConstraint.FormatOptions.directionLeadingToTrailing,
                                                                   metrics: nil, 
                                                                   views: ["visualEffectView":visualEffectView]))

    self.contentView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[visualEffectView]-0-|",
                                                                   options: NSLayoutConstraint.FormatOptions.directionLeadingToTrailing, 
                                                                   metrics: nil, 
                                                                   views: ["visualEffectView":visualEffectView]))

Also you can setup NSVisualEffectView in IB it will be expanded on titlebar.

Answer 2

You need to modify your window's stylemask to include NSFullSizeContentViewWindowMask so that its content view can "overflow" into it.

You can easily accomplish this by adding this line to your AppDelegate:

self.window.styleMask = self.window.styleMask | NSFullSizeContentViewWindowMask;

If you want it to appear dark, like in FaceTime, you need to also add this line of code:

self.window.appearance = NSAppearance(named: NSAppearanceNameVibrantDark)