Setting up buttons in SKScene

Question

I'm discovering that UIButtons don't work very well with SKScene, So I'm attempting to subclass SKNode to make a button in SpriteKit.

The way I would like it to work is that if I initialize a button in SKScene and enable touch events, then the button will call a method in my SKScene when it is pressed.

I'd appreciate any advice that would lead me to finding the solution to this problem. Thanks.

Answer 1

I've made my own Button-Class that I'm working with. SKButton.h:

#import <SpriteKit/SpriteKit.h>
@interface SKButton : SKSpriteNode

@property (nonatomic, readonly) SEL actionTouchUpInside;
@property (nonatomic, readonly) SEL actionTouchDown;
@property (nonatomic, readonly) SEL actionTouchUp;
@property (nonatomic, readonly, weak) id targetTouchUpInside;
@property (nonatomic, readonly, weak) id targetTouchDown;
@property (nonatomic, readonly, weak) id targetTouchUp;

@property (nonatomic) BOOL isEnabled;
@property (nonatomic) BOOL isSelected;
@property (nonatomic, readonly, strong) SKLabelNode *title;
@property (nonatomic, readwrite, strong) SKTexture *normalTexture;
@property (nonatomic, readwrite, strong) SKTexture *selectedTexture;
@property (nonatomic, readwrite, strong) SKTexture *disabledTexture;

- (id)initWithTextureNormal:(SKTexture *)normal selected:(SKTexture *)selected;
- (id)initWithTextureNormal:(SKTexture *)normal selected:(SKTexture *)selected disabled:(SKTexture *)disabled; // Designated Initializer

- (id)initWithImageNamedNormal:(NSString *)normal selected:(NSString *)selected;
- (id)initWithImageNamedNormal:(NSString *)normal selected:(NSString *)selected disabled:(NSString *)disabled;

/** Sets the target-action pair, that is called when the Button is tapped.
 "target" won't be retained.
 */
- (void)setTouchUpInsideTarget:(id)target action:(SEL)action;
- (void)setTouchDownTarget:(id)target action:(SEL)action;
- (void)setTouchUpTarget:(id)target action:(SEL)action;

@end

SKButton.m:

#import "SKButton.h"
#import <objc/message.h>


@implementation SKButton

#pragma mark Texture Initializer

/**
 * Override the super-classes designated initializer, to get a properly set SKButton in every case
 */
- (id)initWithTexture:(SKTexture *)texture color:(UIColor *)color size:(CGSize)size {
    return [self initWithTextureNormal:texture selected:nil disabled:nil];
}

- (id)initWithTextureNormal:(SKTexture *)normal selected:(SKTexture *)selected {
    return [self initWithTextureNormal:normal selected:selected disabled:nil];
}

/**
 * This is the designated Initializer
 */
- (id)initWithTextureNormal:(SKTexture *)normal selected:(SKTexture *)selected disabled:(SKTexture *)disabled {
    self = [super initWithTexture:normal color:[UIColor whiteColor] size:normal.size];
    if (self) {
        [self setNormalTexture:normal];
        [self setSelectedTexture:selected];
        [self setDisabledTexture:disabled];
        [self setIsEnabled:YES];
        [self setIsSelected:NO];

        _title = [SKLabelNode labelNodeWithFontNamed:@"Arial"];
        [_title setVerticalAlignmentMode:SKLabelVerticalAlignmentModeCenter];
        [_title setHorizontalAlignmentMode:SKLabelHorizontalAlignmentModeCenter];

        [self addChild:_title];
        [self setUserInteractionEnabled:YES];
    }
    return self;
}

#pragma mark Image Initializer

- (id)initWithImageNamedNormal:(NSString *)normal selected:(NSString *)selected {
    return [self initWithImageNamedNormal:normal selected:selected disabled:nil];
}

- (id)initWithImageNamedNormal:(NSString *)normal selected:(NSString *)selected disabled:(NSString *)disabled {
    SKTexture *textureNormal = nil;
    if (normal) {
        textureNormal = [SKTexture textureWithImageNamed:normal];
    }

    SKTexture *textureSelected = nil;
    if (selected) {
        textureSelected = [SKTexture textureWithImageNamed:selected];
    }

    SKTexture *textureDisabled = nil;
    if (disabled) {
        textureDisabled = [SKTexture textureWithImageNamed:disabled];
    }

    return [self initWithTextureNormal:textureNormal selected:textureSelected disabled:textureDisabled];
}




#pragma -
#pragma mark Setting Target-Action pairs

- (void)setTouchUpInsideTarget:(id)target action:(SEL)action {
    _targetTouchUpInside = target;
    _actionTouchUpInside = action;
}

- (void)setTouchDownTarget:(id)target action:(SEL)action {
    _targetTouchDown = target;
    _actionTouchDown = action;
}

- (void)setTouchUpTarget:(id)target action:(SEL)action {
    _targetTouchUp = target;
    _actionTouchUp = action;
}

#pragma -
#pragma mark Setter overrides

- (void)setIsEnabled:(BOOL)isEnabled {
    _isEnabled = isEnabled;
    if ([self disabledTexture]) {
        if (!_isEnabled) {
            [self setTexture:_disabledTexture];
        } else {
            [self setTexture:_normalTexture];
        }
    }
}

- (void)setIsSelected:(BOOL)isSelected {
    _isSelected = isSelected;
    if ([self selectedTexture] && [self isEnabled]) {
        if (_isSelected) {
            [self setTexture:_selectedTexture];
        } else {
            [self setTexture:_normalTexture];
        }
    }
}

#pragma -
#pragma mark Touch Handling

/**
 * This method only occurs, if the touch was inside this node. Furthermore if 
 * the Button is enabled, the texture should change to "selectedTexture".
 */
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    if ([self isEnabled]) {
        objc_msgSend(_targetTouchDown, _actionTouchDown);
        [self setIsSelected:YES];
    }
}

/**
 * If the Button is enabled: This method looks, where the touch was moved to.
 * If the touch moves outside of the button, the isSelected property is restored
 * to NO and the texture changes to "normalTexture".
 */
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    if ([self isEnabled]) {
        UITouch *touch = [touches anyObject];
        CGPoint touchPoint = [touch locationInNode:self.parent];

        if (CGRectContainsPoint(self.frame, touchPoint)) {
            [self setIsSelected:YES];
        } else {
            [self setIsSelected:NO];
        }
    }
}

/**
 * If the Button is enabled AND the touch ended in the buttons frame, the
 * selector of the target is run.
 */
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInNode:self.parent];

    if ([self isEnabled] && CGRectContainsPoint(self.frame, touchPoint)) {
        objc_msgSend(_targetTouchUpInside, _actionTouchUpInside);
    }
    [self setIsSelected:NO];
    objc_msgSend(_targetTouchUp, _actionTouchUp);
}

An example: To initialize a button, you write the following lines:

    SKButton *backButton = [[SKButton alloc] initWithImageNamedNormal:@"buttonNormal" selected:@"buttonSelected"];
    [backButton setPosition:CGPointMake(100, 100)];
    [backButton.title setText:@"Button"];
    [backButton.title setFontName:@"Chalkduster"];
    [backButton.title setFontSize:20.0];
    [backButton setTouchUpInsideTarget:self action:@selector(buttonAction)];
    [self addChild:backButton];

Furthermore you need the 'buttonAction' method in your class. * No warranty that this class is working right in every case. I'm still quite new to objective-c. *

Answer 2

I had created a class for using SKSpriteNode as a button quite a while ago. You can find it on GitHub here.

AGSpriteButton

It's implementation is based on UIButton, so if you are already familiar with iOS, you should find it easy to work with.

It can also be assigned a block or an SKAction to be executed when the button is pressed.

It includes a method to set up a label as well.

A button will typically be declared like so:

AGSpriteButton *button = [AGSpriteButton buttonWithColor:[UIColor redColor] andSize:CGSizeMake(300, 100)];
[button setLabelWithText:@"Button Text" andFont:nil withColor:nil];
button.position = CGPointMake(self.size.width / 2, self.size.height / 3);
[button addTarget:self selector:@selector(someSelector) withObject:nil forControlEvent:AGButtonControlEventTouchUpInside];
[self addChild:button];

And that's it. You're good to go.

Answer 3

you could use a SKSpriteNode as your button, and then when the user touches, check if that was the node touched. Use the SKSpriteNode's name property to identify the node:

//fire button
- (SKSpriteNode *)fireButtonNode
{
    SKSpriteNode *fireNode = [SKSpriteNode spriteNodeWithImageNamed:@"fireButton.png"];
    fireNode.position = CGPointMake(fireButtonX,fireButtonY);
    fireNode.name = @"fireButtonNode";//how the node is identified later
    fireNode.zPosition = 1.0;
    return fireNode;
}

Add node to your scene:

[self addChild: [self fireButtonNode]];

Handle touches:

//handle touch events
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInNode:self];
    SKNode *node = [self nodeAtPoint:location];

    //if fire button touched, bring the rain
    if ([node.name isEqualToString:@"fireButtonNode"]) {
         //do whatever...
    }
}

Answer 4

What a lot of great solutions to this problem! For the hardcore scrollers that make it down this far, you're in for a treat! I have subclassed SKScene, and it takes ONE function call to register ANY node to act like a UIButton! Here is the class:

class KCScene : SKScene {
//------------------------------------------------------------------------------------
//This function is the only thing you use in this class!!!
func addButton(_ node:SKNode, withCompletionHandler handler: @escaping ()->()) {
    let data = ButtonData(button: node, actionToPerform: handler)
    eligibleButtons.append(data)
}
//------------------------------------------------------------------------------------
private struct ButtonData {
    //TODO: make a dictionary with ()->() as the value and SKNode as the key.
    //Then refactor this class!
    let button:SKNode
    let actionToPerform:()->()
}

private struct TouchTrackingData {
    //this will be in a dictionary with a UITouch object as the key
    let button:SKNode
    let originalButtonFrame:CGRect
}

private var eligibleButtons = [ButtonData]()
private var trackedTouches = [UITouch:TouchTrackingData]()
//------------------------------------------------------------------------------------
//TODO: make these functions customizable,
//with these implementations as defaults.
private func applyTouchedDownEffectToNode(node:SKNode) {
    node.alpha  = 0.5
    node.xScale = 0.8
    node.yScale = 0.8
}
private func applyTouchedUpEffectToNode(node:SKNode)   {
    node.alpha  = 1
    node.xScale = 1
    node.yScale = 1
}
//------------------------------------------------------------------------------------
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        let touchLocation = touch.location(in: self)
        let touchedNode = atPoint(touchLocation)

        for buttonData in eligibleButtons {
            if touchedNode === buttonData.button {
                //then this touch needs to be tracked, as it touched down on an eligible button!
                for (t, bD) in trackedTouches {
                    if bD.button === buttonData.button {
                        //then this button was already being tracked by a previous touch, disable the previous touch
                        trackedTouches[t] = nil
                    }
                }
                //start tracking this touch
                trackedTouches[touch] = TouchTrackingData(button: touchedNode, originalButtonFrame: touchedNode.frameInScene)
                applyTouchedDownEffectToNode(node: buttonData.button)
            }
        }
    }
}
//------------------------------------------------------------------------------------
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        if trackedTouches[touch] == nil {continue}
        //Now we know this touch is being tracked...
        let touchLocation = touch.location(in: self)
        //TODO: implement an isBeingTouched property on TouchTrackingData, so 
        //applyTouchedDown(Up)Effect doesn't have to be called EVERY move the touch makes
        if trackedTouches[touch]!.originalButtonFrame.contains(touchLocation) {
            //if this tracked touch is touching its button
            applyTouchedDownEffectToNode(node: trackedTouches[touch]!.button)
        } else {
            applyTouchedUpEffectToNode(node: trackedTouches[touch]!.button)
        }

    }
}
//------------------------------------------------------------------------------------
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        if trackedTouches[touch] == nil {continue}
        //Now we know this touch is being tracked...
        let touchLocation = touch.location(in: self)

        if trackedTouches[touch]!.originalButtonFrame.contains(touchLocation) {
            applyTouchedUpEffectToNode(node: trackedTouches[touch]!.button)

            for buttonData in eligibleButtons {
                if buttonData.button === trackedTouches[touch]!.button {
                    buttonData.actionToPerform()
                }
            }
        }
        trackedTouches[touch] = nil
    }
}
//------------------------------------------------------------------------------------
override func touchesCancelled(_ touches: Set<UITouch>?, with event: UIEvent?) {
    for touch in touches! {
        if trackedTouches[touch] == nil {continue}
        //Now we know this touch is being tracked...
        //Since this touch was cancelled, it will not be activating a button,
        //and it is not worth checking where the touch was
        //we will simply apply the touched up effect regardless and remove the touch from being tracked
        applyTouchedUpEffectToNode(node: trackedTouches[touch]!.button)
        trackedTouches[touch] = nil
    }
}
//------------------------------------------------------------------------------------

}

It includes a lot of ideas I haven't yet implemented and some explanations of the code, but just copy and paste it into your project, and you can use it as-is in your own scene. Here is a complete example usage:

class GameScene : KCScene {
var playButton:SKSpriteNode
override init(size:CGSize) {
    playButton = SKSpriteNode(color: SKColor.red, size: CGSize(width:200,height:200))
    playButton.position.x = size.width/2
    playButton.position.y = size.height*0.75
    super.init(size: size)
}
override func didMove(to view: SKView) {
    addChild(playButton)
    addButton(playButton, withCompletionHandler: playButtonPushed)
}
func playButtonPushed() {
    let scene = GameScene(size: CGSize(width: 768, height: 1024))
    scene.scaleMode = .aspectFill
    view!.presentScene(scene)
}
}

The one caveat, is if you implement touchesBegan, touchesMoved, touchesEnded, and/or touchesCancelled you MUST CALL SUPER! Or else it will not work.

And please realize that in that example, there is really only ONE LINE OF CODE you need to give ANY NODE UIButton characteristics! It was this line:

addButton(playButton, withCompletionHandler: playButtonPushed)

I'm always open for ideas and suggestions. Leave 'em in the comments and Happy Coding!!

Oops, I forgot to mention I use this nifty extension. You can take it out of an extension (as you probably don't need it in every node) and plop it in my class. I only use it in one place.

extension SKNode {
var frameInScene:CGRect {
    if let scene = scene, let parent = parent {
        let rectOriginInScene = scene.convert(frame.origin, from: parent)
        return CGRect(origin: rectOriginInScene, size: frame.size)
    }
    return frame
}

}

Answer 5

And since all of us aren't targeting iOS, here's the start of some code I wrote to handle mouse interaction on the Mac.

Question for the gurus: does MacOS offer touch events when using a trackpad? Or are these sent into SpriteKit as mouse events?

Another question for the gurus, shouldn't this class properly be called SKButtonNode?

Anyway, try this...

#if os(iOS)
    override func touchesBegan(touches: NSSet!, withEvent event: UIEvent!)  {
        let touch: AnyObject! = touches.anyObject()
        let touchLocation = touch.locationInNode(parent)

        if (!isEnabled) { return }

        isSelected = true
        if (targetTouchDown != nil && targetTouchDown!.respondsToSelector(actionTouchDown!)) {
            UIApplication.sharedApplication().sendAction(actionTouchDown!, to: targetTouchDown, from: self, forEvent: nil)
        }
    }

    override func touchesMoved(touches: NSSet!, withEvent event: UIEvent!)  {
        if (!isEnabled) { return }

        let touch: AnyObject! = touches.anyObject()
        let touchLocation = touch.locationInNode(parent)

        if (CGRectContainsPoint(frame, touchLocation)) {
            isSelected = true
        } else {
            isSelected = false
        }
    }

    override func touchesEnded(touches: NSSet!, withEvent event: UIEvent!) {
        if (!isEnabled) { return }

        isSelected = false

        if (targetTouchUpInside != nil && targetTouchUpInside!.respondsToSelector(actionTouchUpInside!)) {
            let touch: AnyObject! = touches.anyObject()
            let touchLocation = touch.locationInNode(parent)

            if (CGRectContainsPoint(frame, touchLocation) ) {
                UIApplication.sharedApplication().sendAction(actionTouchUpInside!, to: targetTouchUpInside, from: self, forEvent: nil)
            }
        }

        if (targetTouchUp != nil && targetTouchUp!.respondsToSelector(actionTouchUp!)) {
            UIApplication.sharedApplication().sendAction(actionTouchUp!, to: targetTouchUp, from: self, forEvent: nil)
        }
    }
#else

    // FIXME: needs support for mouse enter and leave, turning on and off selection

    override func mouseDown(event: NSEvent) {
        if (!isEnabled) { return }

        if (targetTouchDown != nil && targetTouchDown!.respondsToSelector(actionTouchDown!)) {
            NSApplication.sharedApplication().sendAction(actionTouchDown!, to: targetTouchDown, from: self)
        }
    }

    override func mouseUp(event: NSEvent) {
        if (!isEnabled) { return }

        if (targetTouchUpInside != nil && targetTouchUpInside!.respondsToSelector(actionTouchUpInside!)) {
            let touchLocation = event.locationInNode(parent)

            if (CGRectContainsPoint(frame, touchLocation) ) {
                NSApplication.sharedApplication().sendAction(actionTouchUpInside!, to: targetTouchUpInside, from: self)
            }
        }

        if (targetTouchUp != nil && targetTouchUp!.respondsToSelector(actionTouchUp!)) {
            NSApplication.sharedApplication().sendAction(actionTouchUp!, to: targetTouchUp, from: self)
        }
    }
#endif

Answer 6

I have used SKButton class by Graf.

I use the SKButton to do scene navigation. i.e present another scene when the user press the SKButton. I get EXC_BAD_ACCESS error at touchesEnded->[self setIsSelected:NO]. This happens especially frequently on the latest iPad with fast CPU.

After checking and troubleshooting, I realised that the SKButton object is already "deallocated" when the setIsSelected function is being called. This is because I use the SKButton to navigate to next scene and this also means that the current scene can be deallocated any time.

I made a small change by putting the setIsSelected in the "else" portion as follows.

Hope this helps for other developer who also see the same error.

(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInNode:self.parent];

    if ([self isEnabled] && CGRectContainsPoint(self.frame, touchPoint)) {
        objc_msgSend(_targetTouchUpInside, _actionTouchUpInside);
    } else {
       [self setIsSelected:NO];
    }
    objc_msgSend(_targetTouchUp, _actionTouchUp);
}