Updating NSView With SubViews and a Memory Leak

That answer is obvious--it leaks because it's a guy.

Could you add some log:

print("Nb of subviews", displayView.subviews.count)
for sub in displayView.subviews {
  sub.removeFromSuperview()
}

And report what you get.

Claude,

The following code shows sub view counts.

class MainViewController: NSViewController {
    @IBOutlet weak var displayView: NSView!
 
    override func viewWillAppear() {
        super.viewWillAppear()
     
        print("No. of subviews before the display view shows up", displayView.subviews.count) // => 0
        for sub in displayView.subviews {
            sub.removeFromSuperview()
        }
    }
 
    override func viewDidAppear() {
        super.viewDidAppear()
     
        for sub in displayView.subviews {
            sub.removeFromSuperview()
        }
        print("No. of subviews after the display view shows up", displayView.subviews.count) // => 0
    }
 
    override func viewWillDisappear() {
        super.viewWillDisappear()
     
        print("No. of subviews right before the display view hides itself", displayView.subviews.count) // => 3
        for sub in displayView.subviews {
            sub.removeFromSuperview()
        }
    }
 
    override func viewDidDisappear() {
        super.viewDidDisappear()
     
        print("No. of subviews after the display view hides itself", displayView.subviews.count) // => 0
    }
}

Initially, the memory consumption stays around 100 MB. After I hide the window and bring it back five times or so, it will go up to around 480 MB.

In this code, we only see views being removed, never added.

Line 16: why do you remove when viesDidAppear (is is just for testing purpose ?)

Where are subviews added ?

What is the size of NSImageView ? Is it a few 100 kB or in the 10 MB to 20 MB?

If the later, probably you reload a new copy of the images in memory.

Where do you inspect the memory used ? In XCode debug session ? Did you look at it with instruments ?

May also have a look here: https://developer.apple.com/documentation/xcode/improving_your_app_s_performance/reducing_your_app_s_memory_use/gathering_information_about_memory_use