Adding the NSObject to the a SKScene - ios

Question

I recently making a racing game with using the SpriteKit. I create an NSObject class called "GameObject" to store all the properties, like physics. I also create another NSObject class called "GameWorld" to store all the game objects, like creating player objects and other objects with their location and the functions of the direction buttons. However, when I start to write a game scene class, I cannot add the world object to the scene, which means the car doesn't show up in the scene. Would anyone can help me about this question? The codes of my SKScene class is provided below,
#interface GamePlay : SKScene
#property (nonatomic) GameWorld *world;
-(void)update:(NSTimeInterval)currentTime;
-(id) initWithSize:(CGSize)s andWorld:(GameWorld *)w;
#end
#implementation GamePlay
- (id) initWithSize:(CGSize)s andWorld:(GameWorld *)w
{
self = [super initWithSize:s];
if (self)
{
_world = w;
}
return self;
}
-(void) didMoveToView:(SKView *)view
{
if (!self.contentCreated ) {
[self createSceneContents];
self.contentCreated = YES;
}
}
-(void) createSceneContents
{
// turn off gravity for the world
self.physicsWorld.gravity = CGVectorMake(0.0f, 0.0f);
self.scaleMode = SKSceneScaleModeAspectFit;
//Create the background
SKSpriteNode *background = [SKSpriteNode spriteNodeWithImageNamed:#"road.png"];
background.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
[self addChild:background];
//Create the buttons for directions
SKSpriteNode *up = [SKSpriteNode spriteNodeWithImageNamed:#"Up.png"];
up.position = CGPointMake(290, 115);
up.name = #"upDirection";
[self addChild:up];
SKSpriteNode *down = [SKSpriteNode spriteNodeWithImageNamed:#"Down.png"];
down.position = CGPointMake(290, 40);
down.name = #"downDirection";
[self addChild:down];
SKSpriteNode *left = [SKSpriteNode spriteNodeWithImageNamed:#"Left.png"];
left.position = CGPointMake(30, 40);
left.name = #"leftDirection";
[self addChild:left];
SKSpriteNode *right = [SKSpriteNode spriteNodeWithImageNamed:#"Right.png"];
right.position = CGPointMake(CGRectGetMidX(self.frame), 40);
right.name = #"rightDirection";
[self addChild:right];
// add objects from GameWorld to this scene using the world's worldNode property
// Here is the place I confuse. the world doesn't show up
[self addChild:_world.worldNode];
}
//making buttons for the cars
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint positionInScene = [touch locationInNode:self];
//setting a node to keep the position of each direction buttons
SKNode *n = [self nodeAtPoint:positionInScene];
NSLog(#"Node n:%#", n);
//compare the location of each SKSpriteNode and the touch location
SKNode *up = [self childNodeWithName:#"upDirection"];
if (n == up) {
[self.world goForward];
}
SKNode *down =[self childNodeWithName:#"downDirection"];
if (n == down) {
[self.world goBackward];
}
SKNode *left = [self childNodeWithName:#"leftDirection"];
if (n == left) {
[self.world goLeft];
}
SKNode *right = [self childNodeWithName:#"rightDirection"];
if (n == right) {
[self.world goRight];
}
}
-(void)update:(NSTimeInterval)currentTime
{
//I don't know how to start yet. = =
}
#end
The GameWorld Class is provided below:
#interface GameWorld : NSObject
#property (nonatomic) SKNode *worldNode;
#property (nonatomic) NSArray *gameObjs;
-(id)init;
-(void) initializeWorld;
-(void) goForward;
-(void) goBackward;
-(void) goLeft;
-(void) goRight;
#end
#implementation GameWorld
-(id)init
{
if (self) {
self = [super init];
GameObject *player = [[GameObject alloc] initWithImageNamed:#"pCar.png" andPosition:CGPointMake(200, 85)];
GameObject *otherCar = [[GameObject alloc]initWithImageNamed:#"AICar.png" andPosition:CGPointMake(200, 100)];
_worldNode = [SKNode node];
// now create the objects, put them in an SKNode
// create the _worldNode with a size equal to the virtual world size
// then add the game objects to that node
_worldNode.scene.size = CGSizeMake(320, 480);
_gameObjs = #[player, otherCar];
}
return self;
}
- (void) initializeWorld
{
// add skSpriteNodes to the worldNode
SKSpriteNode *player = [[SKSpriteNode alloc] initWithImageNamed:#"pCar.png"];
[_worldNode addChild:player];
SKSpriteNode *otherCar = [[SKSpriteNode alloc] initWithImageNamed:#"AICar.png"];
[_worldNode addChild:otherCar];
}
-(void) goForward
{
GameObject *thePlayer = _gameObjs[1];
thePlayer.node.position = CGPointMake(thePlayer.node.position.x, thePlayer.node.position.y + 10);
}
-(void) goBackward
{
GameObject *thePlayer = _gameObjs[1];
thePlayer.node.position = CGPointMake(thePlayer.node.position.x, thePlayer.node.position.y - 10);
}
-(void) goLeft
{
GameObject *thePlayer = _gameObjs[1];
thePlayer.node.position = CGPointMake(thePlayer.node.position.x - 10, thePlayer.node.position.y);
}
-(void) goRight
{
GameObject *thePlayer = _gameObjs[1];
thePlayer.node.position = CGPointMake(thePlayer.node.position.x + 10, thePlayer.node.position.y);
}
#end

Answer 1

There is no need to use NSObject is most cases. Use SKNode and SKSpriteNode instead. By subclassing these classes you can add your custom properties to them.
I suggest you the following structure of the project:
-- GameScene (SKScene)
---- BackgroundLayer (SKNode)
-------- BackgroundNode (SKSpriteNode)
---- UiLayer (SKNode)
-------- your buttons here... (SKSpriteNode)
---- CarLayer (SKNode)
-------- PlayerNode (SKSpriteNode)
-------- OtherCarNode (SKSpriteNode)
In this case you don't have to store objects in manually created arrays, such as gameObjs. For example, all buttons can be accessed from this property: uiLayer.children.
I have created a template, which I use for my Sprite Kit games, take a look on it:
https://github.com/andrew8712/spritekit-game-template