APAppDelegate.h

//
//  APAppDelegate.h
//
//  Created by Sascha Gehlich on 27.04.12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import <Cocoa/Cocoa.h>
#import <Quartz/Quartz.h>

@interface APAppDelegate : NSObject <NSApplicationDelegate>

@property (assign) IBOutlet NSWindow *window;
@property (strong) NSStatusItem *statusItem;

@end

APAppDelegate.m

//...

[[self imageView] setImageZoomFactor:0.5f centerPoint:NSMakePoint(0,0)];

//...