How do I get default title bar height of a NSWindow?

Question

I created an OS/X app that when it runs, I position the window in the center of the screen. In order to do this, it's essential that I include the title bar height in my calculation of the y value.

Is there a way to determine the default title bar? I'd expect (based on my experience with other windowing systems) that I have to query the window manager somehow...

Answer 1

I've come up with this solution. Note that when the window's styleMask includes fullSizeContentView, this returns 0.0, because in that case the titlebar effectively has no height.

As a Swift extension:

extension NSWindow {
    var titlebarHeight: CGFloat {
        frame.height - contentRect(forFrameRect: frame).height
    }
}

Usage:

let titlebarHeight = someWindow.titlebarHeight

As an Objective-C Category-Extension:

@implementation NSWindow (TitleBarHeight)

- (CGFloat) titlebarHeight
{
    return self.frame.size.height - [self contentRectForFrameRect: self.frame].size.height;
}

@end

Usage:

CGFloat titlebarHeight = someWindow.titlebarHeight;