autoreleasepool still gives me a memory leak

So I have this program that displays events on the window using NSWindow and a NSTextField. Basically it tracks the mouse position and the keyboard state.

I created a simple class named MyEventWindow:

//
//  MyEventWindow.h
//  AppTest

#ifndef MyEventWindow_h
#define MyEventWindow_h

@interface MyEventWindow : NSWindow
{
	
}

@property(nonatomic, strong) NSTextField* label;
@property(nonatomic, strong) NSString* labelText;

- (BOOL)windowShouldClose:(id)sender;
- (instancetype) init;
- (void) setLabelText:(NSString *)labelText;


@end

@implementation MyEventWindow

-(instancetype) init
{

	
	self = [super initWithContentRect:NSMakeRect(100, 100, 300, 300)
							styleMask:(NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskMiniaturizable | NSWindowStyleMaskResizable)
							  backing:NSBackingStoreBuffered
								defer:NO];
	if( !self )
	{
		return nil;
	}
	
	[self setTitle: @"Event tracker"];
	[self setIsVisible: YES];
		
	_label = [[NSTextField alloc] initWithFrame:NSMakeRect(5, 100, 290, 100)];
	[_label setBezeled: NO];
	[_label setDrawsBackground: NO];
	[_label setEditable: NO];
	[_label setSelectable: YES];


	NSFont *currentFont = [_label font];


	NSFont *resizedFont = [NSFont fontWithName:[currentFont fontName] size:18];

	
	NSFont *boldFont = [[NSFontManager sharedFontManager] convertFont:resizedFont toHaveTrait:NSFontBoldTrait];

	// convert the bold font to have the italic trait
	NSFont *boldItalicFont = [[NSFontManager sharedFontManager] convertFont:boldFont toHaveTrait:NSFontItalicTrait];

	
	[_label setFont:boldItalicFont];
	
	[_label setTextColor:[NSColor colorWithSRGBRed:0.0 green:0.5 blue:0.0 alpha:1.0]];
	
	// attach label to the damn window
	[[self contentView] addSubview: _label];

	return self;
}

-(BOOL)windowShouldClose:(id)sender
{
	return YES;
}

-(void) setLabelText:(NSString *)newText
{
	[_label setStringValue: newText];
}


@end

#endif /* MyEventWindow_h */

Then in the main file I try to handle event loop manually:

//
//  main.m

#import <Cocoa/Cocoa.h>
#import "MyEventWindow.h"

NSString* NSEventTypeToNSString(NSEventType eventType);
NSString* NSEventModifierFlagsToNSString(NSEventModifierFlags modifierFlags);

int main(int argc, char* argv[])
{
	@autoreleasepool 
	{
	
		[NSApplication sharedApplication];
	
		MyEventWindow* eventWindow = [[MyEventWindow alloc] init];
	
		[eventWindow makeKeyAndOrderFront:nil];
		NSString* log = [NSString string];
	
		// my own message loop
	
		[NSApp finishLaunching];
	
		while (true)
		{
			@autoreleasepool
			{
	
				NSEvent* event = [NSApp nextEventMatchingMask:NSEventMaskAny untilDate: [NSDate distantFuture] inMode:NSDefaultRunLoopMode dequeue:YES];
				
				log = [NSString stringWithFormat:@"Event [type=%@ location={%d, %d} modifierFlags={%@}]", NSEventTypeToNSString([event type]), (int)[event locationInWindow].x, (int)[event locationInWindow].y, NSEventModifierFlagsToNSString([event modifierFlags])];
				
				//NSLog(@"log: %@", log);
				[eventWindow setLabelText: log];
				
				[NSApp sendEvent:event];
				//[NSApp updateWindows]; // redundant?
			}
		}
	}
	
	return 0;
}

NSString* NSEventTypeToNSString(NSEventType eventType) 
{
  	switch (eventType)
	{
		case NSEventTypeLeftMouseDown: return @"LeftMouseDown";
		case NSEventTypeLeftMouseUp: return @"LeftMouseUp";
		case NSEventTypeRightMouseDown: return @"RightMouseDown";
		case NSEventTypeRightMouseUp: return @"RightMouseUp";
		case NSEventTypeMouseMoved: return @"MouseMoved";
		case NSEventTypeLeftMouseDragged: return @"LeftMouseDragged";
		case NSEventTypeRightMouseDragged: return @"RightMouseDragged";
		case NSEventTypeMouseEntered: return @"MouseEntered";
		case NSEventTypeMouseExited: return @"MouseExited";
		case NSEventTypeKeyDown: return @"KeyDown";
		case NSEventTypeKeyUp: return @"KeyUp";
		case NSEventTypeFlagsChanged: return @"FlagsChanged";
		case NSEventTypeAppKitDefined: return @"AppKitDefined";
		case NSEventTypeSystemDefined: return @"SystemDefined";
		case NSEventTypeApplicationDefined: return @"ApplicationDefined";
		case NSEventTypePeriodic: return @"Periodic";
		case NSEventTypeCursorUpdate: return @"CursorUpdate";
		case NSEventTypeScrollWheel: return @"ScrollWheel";
		case NSEventTypeTabletPoint: return @"TabletPoint";
		case NSEventTypeTabletProximity: return @"TabletProximity";
		case NSEventTypeOtherMouseDown: return @"OtherMouseDown";
		case NSEventTypeOtherMouseUp: return @"OtherMouseUp";
		case NSEventTypeOtherMouseDragged: return @"OtherMouseDragged";
		default:
			return [NSString stringWithFormat:@"%lu", eventType];
  	}
}

NSString* NSEventModifierFlagsToNSString(NSEventModifierFlags modifierFlags) 
{
  	NSString* result = @"";
  	if ((modifierFlags & NSEventModifierFlagCapsLock) == NSEventModifierFlagCapsLock) 
		result = [result stringByAppendingString:@"CapsLock, "];
  	if ((modifierFlags & NSEventModifierFlagShift) == NSEventModifierFlagShift)
		result = [result stringByAppendingString:@"NShift, "];
  	if ((modifierFlags & NSEventModifierFlagControl) == NSEventModifierFlagControl)
		result = [result stringByAppendingString:@"Control, "];
  	if ((modifierFlags & NSEventModifierFlagOption) == NSEventModifierFlagOption)
		result = [result stringByAppendingString:@"Option, "];
  	if ((modifierFlags & NSEventModifierFlagCommand) == NSEventModifierFlagCommand)
		result = [result stringByAppendingString:@"Command, "];
  	if ((modifierFlags & NSEventModifierFlagNumericPad) == NSEventModifierFlagNumericPad)
		result = [result stringByAppendingString:@"NumericPad, "];
  	if ((modifierFlags & NSEventModifierFlagHelp) == NSEventModifierFlagHelp)
		result = [result stringByAppendingString:@"Help, "];
  	if ((modifierFlags & NSEventModifierFlagFunction) == NSEventModifierFlagFunction)
		result = [result stringByAppendingString:@"Function, "];
  	return result;
}

in main I added a second @autoreleasepool inside the while loop it seemed to decrease memory usage significanly, however if I keep moving my mouse a lot the memory usage will still increase.

I don't think this should be happening since the labelText is being destroying and recreated each iteration, is something wrong with my code? Why do I have a memory leak here?

Any feedback regarding the code is also appreciated

Cheers