cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   Avizzv92
   Member

   I'm working on a game like Rodents Revenge, just to point out where I'm coming from with this question.

   I have a layer that contains about 168 blocks, these blocks are a subclass of Sprite. Each block contains two instance variables that are integers, one for the xGridLocation and yGridlocation. I have a method that I call that returns an array containing all the blocks that are on the same x or y row as the main character your controlling (the mouse). This method works as long as the blocks stay in the same order (smallest x/y value to largest), but when I start pushing the blocks out of their original row and mixing them up a bit my logic no longer works because it is based on the fact that the blocks in the array are indexed from smallest to largest based on their xGridLocation or yGridLocation.

   My question is how can I go about sorting the array before it's returned in order based on the instance variables xGridLocation and yGridLocation. I was thinking using the sortUsingSelector:@selector(compareValues:) method but wasn't sure how to go about implementing the compareValues method that will do the sorting.

   Here is my method I used for getting an array of blocks.

   //I have another one for x. The y parameter is the mouses y value.
   -(NSMutableArray *)getBlocksForY:(int)y
   {
   	NSMutableArray *blocks = [[NSMutableArray alloc] init];
   
   	int tagNum = 0;
   
           //tagNum starts at 0, and goes up to 168, the numer of children (blocks) on
           //this layer...
   
   	for(tagNum; tagNum<=168; tagNum++)
   	{
   		BlueBlock *currentBlock = (BlueBlock *)[self getChildByTag:tagNum];
   		int currentY = [currentBlock getBlockLocationY];
   
                   //Checks to see if the current block has same y value as the mouse, if
                   //so it adds it to the array.
   		if(currentY == y)
   		{
   			[blocks addObject:currentBlock];
   		}
   	}
   
           //I want to sort before returning...
   	return blocks;
   }

   Thanks in advanced for any help, if you need more information just ask.

   Posted 2 years ago #
2. 

   Lam
   Member

   sortUsingSelector:

   From: http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSMutableArray_Class/Reference/Reference.html#//apple_ref/occ/instm/NSMutableArray/

   sortUsingSelector:
   

   A selector that specifies the comparison method to use to compare elements in the receiver.
   
   The comparator message is sent to each object in the receiver and has as its single argument another object in the array. The comparator method should return NSOrderedAscending if the receiver is smaller than the argument, NSOrderedDescending if the receiver is larger than the argument, and NSOrderedSame if they are equal.

   From the description it pretty much means you need a selector with the signature
   

   - (NSComparisonResult) compareValue:(id) objectToCompare;

   Otherwise another neat way is to create a category to extend the NSArray into an always sorted array using any basic sorting mechanism (binary, merge, quicksort) internally.

   So what I could do is:
   

   @implementation NSMutableArray (BinarySortedArray)
   - (void) addObject:(id)object sortedBy:(SEL)compareSelector
   {
    ...
   }
   
   ... later on in your code
   
   NSMutableArray *aSortedArray = [NSMutableArray array];
   [aSortedArray addObject: mongoose sortedBy:@selector(mongooseCompare:)];

   Posted 2 years ago #
3. 

   Avizzv92
   Member

   Thanks for your assistance, with your tips and some help from another person I got something working for my needs.

   Posted 2 years ago #

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