@class Chunk;

@protocol ChunkDelegate
@required
- (CGFloat)heightForChunk:(Chunk *)chunk;
@end

@interface ChunkController ()<ChunkDelegate>

@property (nonatomic, strong) Game *game;

@end

@implementation ChunkController

- (void)createChunks;
{
  // create chunks here
  Chunk *chunk = [[Chunk alloc] initWithDelegate:self]
}

- (CGFloat)heightForChunk:(Chunk *)chunk;
{
  // calculate height for the chunk here
}

@end

@interface Chunk

@property (nonatomic, weak) id<ChunkDelegate> delegate;

- (instancetype)initWithDelegate:(id<ChunkDelegate>)delegate;

@end

@implementation Chunk

- (instancetype)initWithDelegate:(id<ChunkDelegate>)delegate;
{
    self = [super init];
    if (self) {
        self.delegate = delegate;
    }
    return self;
}

@end