iOS Loading plist into array and randomly grabbing item filename

[acctman]

Hi currently my game is loading fl_gfood.png or fl_bfood.png from the fl_food.plist. That works fine but now I have 17 bad food items .png and 17 good food items .png. My question is how do I randomly display one of the 17 items from each group? I was told to load the plist into an array and then randomly grab an item filename using arc4random, but how do I do that?

@implementation Food

+ (void)loadAssets {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [[FLSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile:[AssetHelper getDeviceSpecificFileNameFor:@"fl_food.plist"]];
    });

}

- (id)init {
    self = [super init];
    if (self) {
        self.size                   = CGSizeMake(16 * __HIGHRES_SCALE, 16 * __HIGHRES_SCALE);
        self.offset                 = CGPointMake(8 * __HIGHRES_SCALE, 8 * __HIGHRES_SCALE);
        self.removeAfterCollision   = YES;
        self.collideable            = NO;
        self.score                  = 10;
    }
    return self;
}

- (FLSprite *)sprite {
    if(_sprite == nil) {

        if(self.score < 10) {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_gfood.png"];
        } else {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_bfood.png"];
        }
    }
    return _sprite;
}

 

[larswik]

That should not be that hard. If you are storing png's in an array you must be storing them as NSData objects. Use the arcrRandom% myArray.count to set the max number of guesses. Then restore your PNG's from the NSData objects located at the selected index and add them as subViews to you view.

If arc4Random is confusing you google it. There are many examples out there, that is how I originally found a random number generator.

 

[dejo]

If you are storing png's in an array you must be storing them as NSData objects.

Not necessarily. NSArrsys can hold all types of objects, including UIImages.

 

[ArtOfWarfare]

The only things NSArrays can't hold are primitives (but boxing is now easy with the @ syntax) and structs (and unions, not that I'd expect anyone to be using those in an iOS app.)

 

[dejo]

My question is how do I randomly display one of the 17 items from each group? I was told to load the plist into an array and then randomly grab an item filename using arc4random, but how do I do that?

Divide-and-conquer, as it were. Describe to us, in pseudo-code if necessary, the steps you think are needed in order to solve this problem. Which steps are you comfortable coding yourself and with which steps do you require further assistance?

 

[Duncan C]

The only things NSArrays can't hold are primitives (but boxing is now easy with the @ syntax) and structs (and unions, not that I'd expect anyone to be using those in an iOS app.)

Oops. I misread your post. I thought you said the only thing NSArrays CAN hold are primitives and structs.


As far as unions, I could see using them to look at pixel data as arrays of bytes or as RGB/RGBA groups, or something like that.

----------

Hi currently my game is loading fl_gfood.png or fl_bfood.png from the fl_food.plist. That works fine but now I have 17 bad food items .png and 17 good food items .png. My question is how do I randomly display one of the 17 items from each group? I was told to load the plist into an array and then randomly grab an item filename using arc4random, but how do I do that?

@implementation Food

+ (void)loadAssets {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [[FLSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile:[AssetHelper getDeviceSpecificFileNameFor:@"fl_food.plist"]];
    });

}

- (id)init {
    self = [super init];
    if (self) {
        self.size                   = CGSizeMake(16 * __HIGHRES_SCALE, 16 * __HIGHRES_SCALE);
        self.offset                 = CGPointMake(8 * __HIGHRES_SCALE, 8 * __HIGHRES_SCALE);
        self.removeAfterCollision   = YES;
        self.collideable            = NO;
        self.score                  = 10;
    }
    return self;
}

- (FLSprite *)sprite {
    if(_sprite == nil) {

        if(self.score < 10) {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_gfood.png"];
        } else {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_bfood.png"];
        }
    }
    return _sprite;
}

        if(self.score < 10) {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_gfood.png"];
        } else {
            _sprite = [FLSprite spriteWithSpriteFrameName:@"fl_bfood.png"];
        }

Your code above is using a fixed filename to load a fixed good or bad sprite image.

What are the filenames for for your variety of images?

If you use filenames like
fl_gfood_0.png
fl_gfood_1.png
fl_gfood_2.png
fl_gfood_3.png
...
Then you could:

Generate a random number from 0 to 16 using arc4random_uniform(17)
Build a filename using that number and the NSString class method stringWithFormat.

Pass the resulting filename to your spriteWithSpriteFrameName method.

 

[larswik]

Not necessarily. NSArrsys can hold all types of objects, including UIImages.

True. He said png files and I always store that data in NSData since you can write that to plists.

 

[acctman]

Thanks for all the help.

 

[Duncan C]

Thanks for all the help.

Did you solve your problem, then?