UITouch methods in an object not working properly - ios

Question

I have got a SKScene name “Scene” in which I instantiate 2 objects of my class “Button” subclass of SKNode.
In order to not multiply the number of lines of code in my SKScene, I wanted to implemente the touch methods directly in my class “Button”.
Here is the code :
Scene.h
#import <SpriteKit/SpriteKit.h>
#interface Scene : SKScene
#end
Scene.m
#import "Scene.h"
#import "Button.h"
#implementation Scene
- (id)initWithSize:(CGSize)size
{
if (self = [super initWithSize:size])
{
Button *button01 = [Button node];
[button01.number setString: #"1"];
button01.position = CGPointMake(CGRectGetMidX(self.frame) - 50, 160);
Button *button02 = [Button node];
[button02.number setString: #"2"];
button02.position = CGPointMake(CGRectGetMidX(self.frame) + 50, 160);
[self addChild:button01];
[self addChild:button02];
}
return self;
}
#end
Button.h
#import <SpriteKit/SpriteKit.h>
#interface Button : SKNode
#property (strong, nonatomic) NSMutableString *number;
#end
Button.m
#import "Button.h"
SKShapeNode *button;
#implementation Button
- (id)init
{
if (self = [super init])
{
self.userInteractionEnabled = YES;
_number = [[NSMutableString alloc] init];
[_number setString: #"0"];
button = [SKShapeNode node];
[button setPath:CGPathCreateWithRoundedRect(CGRectMake(-25, -25, 50, 50), 4, 4, nil)];
button.fillColor = [SKColor clearColor];
button.lineWidth = 1.0;
button.strokeColor = [SKColor whiteColor];
button.position = CGPointMake(0, 0);
SKLabelNode *label = [SKLabelNode labelNodeWithFontNamed:#"Arial"];
label.text = _number;
label.fontSize = 20;
label.verticalAlignmentMode = SKLabelVerticalAlignmentModeCenter;
label.position = CGPointMake(0, 0);
label.fontColor = [SKColor whiteColor];
[button addChild:label];
[self addChild:button];
}
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
if(CGRectContainsPoint(button.frame, location))
{
button.fillColor = [SKColor whiteColor];
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
button.fillColor = [SKColor clearColor];
}
#end
The problem is when I touch inside the button01, it’s the button02 color’s which change. As if the action is only apply on the last instance of my class.
How can I fixe this.
Thanks in advance.

Answer 1

The issue is the following variable has global scope in your Button class:
SKShapeNode *button;
Since it is shared among the instances of Button, it contains a reference to the SKShapeNode of the last Button that was instantiated. In this case, button 2. You can resolve this issue by defining button as an instance variable:
#implementation Button
{
SKShapeNode *button;
}
...

Answer 2

For some reasons your Button has SKNode as a superclass. SKNode doesn't have a size property, which you can change, so it takes the whole size of it's parent node. Consider it as a layer of the scene. So wherever you touch, the latest SKScene's child (which is button02 in your case) will receive the touch.
Solution: Define Button as a subclass of SKShapeNode directly.