iPhone Game Development

Game State Serialization

Now that we have implemented our levels, we need a way to show the progression between them and a way to jump between levels and the menu. This presents us with three tasks:

• We need to store an integer value that represents how many levels have been unlocked.

• When the player completes a level for the first time, we need to increment that value.

• From our Main menu, we list all of the playable levels; we want to gray out the links to levels that are currently locked.

Initialize Storage

We begin by adding the integer to our persistent storage in the Game2DAppDelegate class. Therefore, we will add the following to our applicationDidFinishLaunching: function:

//Game2DAppDelegate.m
//setup default save data.
if([g_ResManager getUserData:ProgressionSavefile] == nil){
    //progression will store the unlocked level count, from 0..3.
    [g_ResManager storeUserData:[NSNumber numberWithInt:0]
                toFile:ProgressionSaveFile];
}

where ProgressionSaveFile is defined as:

#define ProgressionSaveFile @"progression"

End Game

Within our GLESGameStates, we have already written code to determine win and loss states. Now we will write some functions that all of our levels can use to handle user input and rendering for the end states (win or lose) and increment the progression integer.

We modify the GLESGameState class:

@interface GLESGameState : GameState { int endgame_state; @private float endgame_complete_time; } //... code snipped #define ENDGAME_GAME_IN_PROGRESS 0 #define ENDGAME_WINNING 1 #define ...