NSButton wont setFont: when layer backed - objective-c

Question

I have my NSButton layer backed because I wanted to use a custom image, but this seems like it's inhibiting the use of the setFont: method when I need to programmatically change the font, as when I comment out the code for wantsUpdateLayer: and updateLayer:, setFont: works, but when the layer methods are in the code, it does nothing.
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
self.fontChangeButton = [[CustomButton alloc]initWithFrame:NSMakeRect(82, 60, 190, 113)];
[self.window.contentView addSubview:self.fontChangeButton];
}
- (IBAction)changeFont:(id)sender {
[self.fontChangeButton fontChange];
}
#end
#implementation CustomButton
- (void)fontChange{
[self setFont:[NSFont fontWithName:#"Dosis Bold" size:40]];
}
//when these are commented out, setFont: works, but I need them in for the custom button images
- (BOOL)wantsUpdateLayer{
return YES;
}
- (void)updateLayer{
if (self.state == NSOnState) {
self.layer.contents = [NSImage imageNamed:#"buttonPressed.png"];
}else
self.layer.contents = [NSImage imageNamed:#"buttonUnpressed.png"];
}
This thread offers a workaround, but I'd much rather understand why this is happening and fix it: Can't Change NSButton Font

Answer 1

By overriding -wantsUpdateLayer to return YES you're bypassing calls to -drawRect:. This facility was introduced in 10.8 and exists for efficiency purposes.
There are two things I think should be clarified:
1 - You don't need to override -wantsUpdateLayer to be layer-backed. Just send -setWantsLayer:YES to your button to be layer-backed.
2 - In your example, creating a custom NSButtonCell class might be a better approach to what you're trying to do. Have a look at Apple's documentation on subclassing NSControl and this how to to get started.