Need help with looping through an array

[Zanzibar7]

I'm trying to make a game where you move your player around the screen and collect gold bars. I made an array that i'm going to keep all of my gold bars in, and I want to loop through that array and check for a collision between the player and each gold bar. In my code right now I only have one gold bar but later on I plan on making several different levels that use different numbers of gold bars, so that's why I want a mutable array.

In the header file I have this:

@interface Game1ViewController : UIViewController {
UIImageView *goldBar;
NSMutableArray *goldBars;
}
@property (nonatomic, retain) IBOutlet UIImageView *goldBar;
@property (nonatomic, retain) NSMutableArray *goldBars;

In the implementation file I have this:

@implementation Game1ViewController
@synthesize goldBar;
@synthesize goldBars;
- (void)viewDidLoad {
	[goldBars addObject:goldBar];
}
- (void)gameStatePLayNormal {
	// collision between player and each gold bar
	for (UIImageView *image in goldBars) {
		if (CGRectIntersectsRect(player.frame, image.frame)) {
			score++;
			[goldBars removeObject:image];
		}
	}
}
- (void)viewDidUnload {
	self.goldBar = nil;
}
- (void)dealloc {
	[goldBar release];
	[goldBars release];
}

That's all the code relevant to my question. I don't receive any errors when I run it, but it doesn't do anything in the for loop. I think there is something I have to do in the viewDidLoad method to initialize the array but i don't know exactly what I need to do. Is there a better way of doing this or am I on the right track, and what do I need to do to get my for-loop working? Thanks in advance for any help.

[Domele]

You need to initialize your array.

[SundialSoft]

Originally Posted by Zanzibar7

I'm trying to make a game where you move your player around the screen and collect gold bars. I made an array that i'm going to keep all of my gold bars in, and I want to loop through that array and check for a collision between the player and each gold bar. In my code right now I only have one gold bar but later on I plan on making several different levels that use different numbers of gold bars, so that's why I want a mutable array.

In the header file I have this:

@interface Game1ViewController : UIViewController {
UIImageView *goldBar;
NSMutableArray *goldBars;
}
@property (nonatomic, retain) IBOutlet UIImageView *goldBar;
@property (nonatomic, retain) NSMutableArray *goldBars;

In the implementation file I have this:

@implementation Game1ViewController
@synthesize goldBar;
@synthesize goldBars;
- (void)viewDidLoad {
	[goldBars addObject:goldBar];
}
- (void)gameStatePLayNormal {
	// collision between player and each gold bar
	for (UIImageView *image in goldBars) {
		if (CGRectIntersectsRect(player.frame, image.frame)) {
			score++;
			[goldBars removeObject:image];
		}
	}
}
- (void)viewDidUnload {
	self.goldBar = nil;
}
- (void)dealloc {
	[goldBar release];
	[goldBars release];
}

That's all the code relevant to my question. I don't receive any errors when I run it, but it doesn't do anything in the for loop. I think there is something I have to do in the viewDidLoad method to initialize the array but i don't know exactly what I need to do. Is there a better way of doing this or am I on the right track, and what do I need to do to get my for-loop working? Thanks in advance for any help.

As stated you need an alloc/init statement:

       goldBars = [[NSMutableArray alloc] init];

or you could initWithObjects and add your initial bars that way.

Have you decided how to write the game yet? 2D or 3D. Just asking because there's a nice demo for Cocos3D using the accelerometer to move around 'catching' blocks so may be similar to what you plan to do.

[Zanzibar7]

Thanks, I got it to work now. I knew I was missing something simple like like that, but I couldn't figure out how to write it.

[Zanzibar7]

Originally Posted by SundialSoft

Have you decided how to write the game yet? 2D or 3D. Just asking because there's a nice demo for Cocos3D using the accelerometer to move around 'catching' blocks so may be similar to what you plan to do.

It's a 2d game and I know I should probably be using cocos2d to make it, and I might recreate it later using cocos2d, but for now I'm going to stick with the regular frameworks. I'm not really in the mood right now to learn how to use it.

[Naughty_Ottsel]

The others have answered correctly however for convenience it may be helpful to remove the @synthesize goldBars and lazily instantiate the array:

-(NSMutableArray *)goldBars
{
if (!_goldBars) _goldBars = [[NSMutableArray alloc]init];
}
return _goldBars
}

Its not majorly important, but means you aren't creating the array until it is needed and that is simply done via the usual dot notation, or calling this method. It always helps to remember that unless it is in the .xib and non primitive properties are not inited through the @property/@synthesize calls.