XCode Cocoa/Objective-C Saving program data

I am relatively new to Objective-C and Cocoa and have built an application in which I want to be able to save the current data. (AS in File - Save As - countDown.cd or somthing)
After the save you could then Open the saved file and it would restore the app with the appropriate data etc...

What is the best way of doing this?
I know I can obviously make a text file with the stored data in key pairs and then parse on an open but is there a better/more standard approach.

Thanks.

 

Thanks a bunch. I will check it out.

 

Ok so I checked it out and I thought I got it to work but I have a problem.

Does anyone have an idea why this doesn't update my NSDatePicker when I load the saved file?

Code:

- (NSData *)dataRepresentationOfType:(NSString *)aType
{
    NSDate* date = [datePicker dateValue];
    return [NSKeyedArchiver archivedDataWithRootObject: date];
}

- (BOOL)loadDataRepresentation:(NSData *)data ofType:(NSString *)aType
{
    NSLog(@"About to read data of type %@", aType);
	NSDate* date;
	date = [NSKeyedUnarchiver unarchiveObjectWithData:data];	
	if(date == nil){
		NSLog(@"Test");
		return NO;
	}
	else{
		[datePicker setDateValue: date];
		return YES;
	}
	return YES;
}