macOS How should I spawn the new threads?

myTimer = [NSTimer scheduledTimerWithTimeInterval: secondsBetweenSaves target: self selector: @selector(timerWorker:) userInfo: nil repeats: YES];

- (void) timerWorker:(NSTimer*)myTimer {
	PGApplication *pagesApp = [[PGApplication alloc] initWithBundleID: @"com.apple.iWork.Pages"];
	NMApplication *numbersApp = [[NMApplication alloc] initWithBundleID: @"com.apple.iWork.Numbers"];
	KYApplication *keynoteApp = [[KYApplication alloc] initWithBundleID: @"com.apple.iWork.Keynote"];
	//NSError *myError = nil;
	//id result;
	
	// Save Pages Docs
	if ([pagesApp isRunning] && savePages) {
		PGReference *realRef = [pagesApp documents];
		NSNumber *numDocs = [[[pagesApp count] each: [PGConstant document]] send];
		[self doSaves: realRef andNumDocs: numDocs];
	} // end pagesApp if
	
	// Save Numbers Docs
	if ([numbersApp isRunning] && saveNumbers) {
		NMReference *realRef = [numbersApp documents];
		NSNumber *numDocs = [[[numbersApp count] each: [NMConstant document]] send];
		[self doSaves:realRef andNumDocs:numDocs];
	} // End if

	// Save Keynote Docs
	if ([keynoteApp isRunning] && saveKeynote) {
		KYReference *realRef = [keynoteApp documents];
		NSNumber *numDocs = [[[keynoteApp count] each: [KYConstant document]] send];
		[self doSaves:realRef andNumDocs:numDocs];
	}
	
	// Dealloc
	[pagesApp release];
	[numbersApp release];
	[keynoteApp release];
}

- (void) doSaves:(ASReference*)realRef andNumDocs:(NSNumber*)numDocs {
	SEApplication *systemApp = [SEApplication applicationWithName: @"System Events"];
	// Protect method.  Anything but these three might bork program...
	if ([realRef isKindOfClass: [PGReference class]] || [realRef isKindOfClass: [KYReference class]] || [realRef isKindOfClass: [NMReference class]]) {
		// The methods I'm using here are all shared by PGReference, KYReference, and NMReference.
		PGReference *myRef =  (PGReference *)realRef;
		for (int i = 1; i <= [numDocs intValue]; i++) {
			BOOL isModified = [[[[myRef at: i] modified] getItem] boolValue];
			NSString *docPath;
			// Request save
			/************************************/
			/* This is what stalls the menulet. */
			/************************************/
			if (isModified) {
				[[[myRef at: i] save] send];
				docPath = [[[myRef at: i] path] getItem];
			}
			/****************************/
			/*     End stalling code    */
			/****************************/
			// Archive saves?
			if (archiveSaves && isModified && ![docPath isKindOfClass:[NSNull class]]) {
				// Some setup
				NSString *timeStamp = [[NSDate date] descriptionWithCalendarFormat: @"_%Y-%m-%d_%H-%M-%S_" timeZone: nil locale: nil];
				// The document's name
				NSString *docName = [[[myRef at: i] name] getItem];
				// POSIX path sans document name
				SEReference *docRef = [[[systemApp files] byName: docPath] container];
				NSString *docContainer = [NSString stringWithFormat: @"%@/", [[docRef POSIXPath] getItem]];
				// Target path for zip archive with timestamp.
				NSString *targetPath = [NSString stringWithFormat:@"%@%@%@.zip", docContainer, timeStamp, docName];
				// The actual archiving
				NSTask *archiveTask = [[NSTask alloc] init];
				[archiveTask setLaunchPath: @"/usr/bin/ditto"];
				NSArray *arguments = [NSArray arrayWithObjects: @"-ck", docPath, targetPath, nil];
				[archiveTask setArguments: arguments];
				[archiveTask launch];
				[archiveTask release];
			} // End Archive Saves
		} // End for
	}
}