Set aspectRatio of the main window on MacOS - objective-c

Question

I need to make main window to preserve width/height ratio when the user resizes it on MacOS.
My first idea was to handle the following notification:
#interface Override_iOS : NSObject
#end
__strong Override_iOS *_instance;
#implementation Override_iOS
+(void)load
{
NSLog(#"[Override_iOS load]");
_instance = [Override_iOS new];
[[NSNotificationCenter defaultCenter] addObserver:_instance
selector:#selector(applicationDidFinishLaunching:)
name:UIApplicationDidFinishLaunchingNotification
object:nil];
}
-(void)applicationDidFinishLaunching:(NSNotification*) notification
{
NSLog(#"[Override_iOS applicationDidFinishLaunching:%#]", notification);
//qDebug() << "applicationDidFinishLaunching handler";
}
#end
and try to set something like aspectRatio property of the main window, but looks like that this code would not work on MacOS, but only on iOS (at least in my app).
Is it possible to do something like this on MacOS?
Is there an option in XCode project?
EDIT1
I need something like this:
- (void)awakeFromNib {
// Keep the aspect ratio constant at its current value
[window setAspectRatio:window.frame.size];
}
but it is not clear where to add this.
EDIT1
Created a test app:

Answer 1

I have done very little with MacOS apps, but this may be what you're looking for...
Create a NSWindow subclass:
MyWindowController.h
#import <Cocoa/Cocoa.h>
NS_ASSUME_NONNULL_BEGIN
#interface MyWindowController : NSWindowController
#end
NS_ASSUME_NONNULL_END
MyWindowController.m
#import "MyWindowController.h"
#interface MyWindowController ()
#end
#implementation MyWindowController
- (void)windowDidLoad {
[super windowDidLoad];
// set the aspect ratio here
[self.window setAspectRatio:NSMakeSize(320.0, 640.0)];
}
#end
Then assign the custom class of your window controller: