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POInitializing a static singleton object with NSCoder
 

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    <p>I'm working on an iPhone app and facing some troubles with my shared singleton class. I'm using a shared singleton to store two variables <code>int gameRuns</code> and <code>int totalScore</code> 'gamRuns' just increments every time the user loads the app, and 'totalScore' is obvious :D</p> <p>the issue is as follows, I load the singleton and init using my own method when the app loads using this code:</p> <pre><code>+ (SingletonLevelState*)sharedLevelStateInstance { static SingletonLevelState *sharedLevelStateInstance; @synchronized(self) { if(!sharedLevelStateInstance) { //Init a singleton sharedLevelStateInstance = [[SingletonLevelState alloc] init]; sharedLevelStateInstance-&gt;gameRuns = 1; sharedLevelStateInstance-&gt;totalScore = 0; } } return sharedLevelStateInstance; } </code></pre> <p>This is working great as I can reference this class from any other class and always get a pointer to the same object, so this works fine from other objects:</p> <pre><code>sharedLevelState = [SingletonLevelState sharedLevelStateInstance]; sharedLevelStateInstance.gameRuns++; </code></pre> <p>Now I added the NSCoder protocol, and added the two methods <code>initWithCoder</code> and <code>encodeWithCoder</code> as follows :</p> <pre><code>- (void) encodeWithCoder: (NSCoder *)coder { //encode level data [coder encodeInt:self-&gt;gameRuns forKey:@"gameRuns"]; [coder encodeInt:self-&gt;totalScore forKey:@"totalScore"]; } - (id) initWithCoder: (NSCoder *) coder { if(self = [super init]){ self-&gt;gameRuns = [coder decodeIntForKey:@"gameRuns"]; self-&gt;totalScore = [coder decodeIntForKey:@"totalScore"]; } return self; } </code></pre> <p>Now when the app loads, I check to see if we already have a saved sate, if it exists, I just unarchive the class with that file, if not, I init that class using my custom method above, then set its defaults, encode it to file so we have a saved state, here's the code:</p> <pre><code> //Load Level state sharedLevelStateInstance = [SingletonLevelState sharedLevelStateInstance]; //Check if file is saved NSFileManager *fm = [[NSFileManager alloc] init]; NSString *gameStatePath = [NSString stringWithString:[self getSavePath]]; if([fm fileExistsAtPath:gameStatePath]){ [self loadState]; sharedLevelStateInstance.gameRuns = sharedLevelStateInstance.gameRuns+1; NSLog(@"Loaded %d times", [sharedLevelStateInstance gameRuns]); } [fm release]; </code></pre> <p>Now the last line in the if statement works perfectly, it increments every time I load the app as expected and <em>I feel really happy</em> lol.</p> <p><em>However, the problem arises</em> when I try to get a reference of the singleton in another class by doing the following:</p> <pre><code>sharedLevelStateInstance = [SingletonLevelState sharedLevelStateInstance]; NSLog(@"Played: %d times", sharedLevelStateInstance.gameRuns); </code></pre> <p>It always counts back to 1, I know what happens but I'm not sue what's the best way to solve it, when I <code>initWithCoder</code> the singleton, It's not returning a static object, it creates a new one, when I init my <code>sharedLevelStateInstance</code>, it calls my first custom method, initializing it to the defaults hardcoded.</p> <p>So StackOverflow, can you please help me ?!</p> <p>I just need to know what's the best way to get a reference to the same object without allocating a new one every time I <code>initWithCoder</code> !</p> <p>Thanks :)</p>
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