Where can I find a generic game state singleton for Objective C? - objective-c

Question

I'm wanting to use, and store a game state singleton inside NSCoder, but I am finding it quite difficult to find a generic state management that saves and loads its data using the NSKeyedArchiver/NSCoder routines.
I'm wondering if someone can direct me to a good tutorial, or generic code for use as a game state singleton, with it saving/loading in NSCoder?
Thanks

Answer 1

I've been able to get a basic game state manager working from watching tutorials from 71squared.com
I use the SynthesizeSingleton.h from CocoaWithLove and am able to save and load states using NSCoder / archiving.
As it uses the singelton, I can reference it by writing:
GameStateManager *gsm = [GameStateManager sharedGameStateManager];
As below:
// GameStateManager.h file
#interface GameStateManager : NSObject
{
NSMutableArray *listOfPlayers;
}
#property (nonatomic, retain) NSMutableArray *listOfPlayers;
+ (GameStateManager *)sharedGameStateManager;
-(void)loadGameState;
-(void)saveGameState;
// GameStateManager.m
#import "GameStateManager.h"
#import "SynthesizeSingleton.h"
#import "Player.h"
#implementation GameStateManager
SYNTHESIZE_SINGLETON_FOR_CLASS(GameStateManager)
#synthesize listOfPlayers;
#pragma mark - Init
- (id)init
{
self = [super init];
if (self) {
// Initialization code here.
self.listOfPlayers = [NSMutableArray array];
}
return self;
}
#pragma mark - Memory management
-(void) dealloc
{
[super dealloc];
}
#pragma mark - Save/Load
-(void)saveGameState
{
NSLog(#"saveGameState");
// Set up the game state path to the data file that the game state will be save to
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *gameStatePath = [documentsDirectory stringByAppendingPathComponent:#"gameState.dat"];
// Set up the encoder and storage for the game state data
NSMutableData *gameData;
NSKeyedArchiver *encoder;
gameData = [NSMutableData data];
encoder = [[NSKeyedArchiver alloc] initForWritingWithMutableData:gameData];
// Archive the object
[encoder encodeObject:self.listOfPlayers forKey:#"playerObjects"];
// Finish encoding and write to disk
[encoder finishEncoding];
[gameData writeToFile:gameStatePath atomically:YES];
[encoder release];
}
-(void)loadGameState
{
NSLog(#"loadGameState");
// Set up the game state path to the data file that the game state will be save to
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *gameStatePath = [documentsDirectory stringByAppendingPathComponent:#"gameState.dat"];
NSMutableData *gameData;
NSKeyedArchiver *decoder;
gameData = [NSData dataWithContentsOfFile:gameStatePath];
// Check to see if the .dat file exists, and load contents
if (gameData)
{
decoder = [[[NSKeyedUnarchiver alloc] initForReadingWithData:gameData] retain];
self.listOfPlayers = [[[decoder decodeObjectForKey:#"playerObjects"] retain] autorelease];
NSLog(#"Returned %d players", [self.listOfPlayers count]);
for (Player *p in self.listOfPlayers)
{
NSLog(#"p.name = %#", p.fname);
}
// Finished decoding, release
[decoder release];
[decoder autorelease];
} else {
}
}
In my Player.h/.m file I do this:
#interface Player : NSObject
<NSCoding>
{
NSString *fname;
}
#property(nonatomic,retain) NSString *fname;
// Player.m file
#pragma mark - Encoding
-(id)initWithCoder:(NSCoder *)aDecoder
{
//[self initWithObject:[aDecoder decodeObject];
self = [super init];
if (self) {
// Initialization code here.
self.fname = [aDecoder decodeObjectForKey:#"fname"];
}
return self;
}
-(void)encodeWithCoder:(NSCoder *)aCoder
{
[aCoder encodeObject:self.fname forKey:#"fname"];
}
// ---
My follow-up questions are:
1) Am I meant to put a listOfPlayers in the GameStateManager?
--> Moved to a new question
2) In my encoder, I have to store each field individually, is it not possible to just store the actual object itself?
3) Does encoding of an object also encode all its children?
Lets say I have a Parent class (Player) and a Child class (Weapons). If I encode the Player object only, will it encode all the Weapons too automatically because they are linked?
Thanks.