Zoom and Scroll SKNode in SpriteKit

ios, iphone, scroll, sprite-kit, uiscrollview

Solution

This is how I would do this:

Setup:

- Create a GameScene as the rootNode of your game. (child of SKScene)

- Add BoardNode as child to the scene (child of SKNode)

- Add CameraNode as child to the Board (child of SKNode)

- Add LetterNodes as children of the Board

Keep Camera node centered:

// GameScene.m
- (void) didSimulatePhysics
{
     [super didSimulatePhysics];
     [self centerOnNode:self.Board.Camera];
}

- (void) centerOnNode:(SKNode*)node
{
    CGPoint posInScene = [node.scene convertPoint:node.position fromNode:node.parent];
    node.parent.position = CGPointMake(node.parent.position.x - posInScene.x, node.parent.position.y - posInScene.y);
}

Pan view by moving BoardNode around (Remember to prevent panning out of bounds)

// GameScene.m
- (void) handlePan:(UIPanGestureRecognizer *)pan
{
    if (pan.state == UIGestureRecognizerStateChanged)
    {
        [self.Board.Camera moveCamera:CGVectorMake([pan translationInView:pan.view].x, [pan translationInView:pan.view].y)];
    }
}

// CameraNode.m
- (void) moveCamera:(CGVector)direction
{
    self.direction = direction;
}

- (void) update:(CFTimeInterval)dt
{
    if (ABS(self.direction.dx) > 0 || ABS(self.direction.dy) > 0)
    {
        float dx = self.direction.dx - self.direction.dx/20;
        float dy = self.direction.dy - self.direction.dy/20;
        if (ABS(dx) < 1.0f && ABS(dy) < 1.0f)
        {
            dx = 0.0;
            dy = 0.0;
        }
        self.direction = CGVectorMake(dx, dy);
        self.Board.position = CGPointMake(self.position.x - self.direction.dx, self.position.y + self.direction.dy);
    }
}

// BoardNode.m
- (void) setPosition:(CGPoint)position
{
    CGRect bounds = CGRectMake(-boardSize.width/2, -boardSize.height/2, boardSize.width, boardSize.height);

    self.position = CGPointMake(
        MAX(bounds.origin.x, MIN(bounds.origin.x + bounds.size.width, position.x)),
        MAX(bounds.origin.y, MIN(bounds.origin.y + bounds.size.height, position.y)));
}

Pinch Zoom by setting the size of your GameScene:

// GameScene.m
- (void) didMoveToView:(SKView*)view
{
    self.scaleMode = SKSceneScaleModeAspectFill;
}

- (void) handlePinch:(UIPinchGestureRecognizer *)pinch
{
    switch (pinch.state)
    {
        case UIGestureRecognizerStateBegan:
        {
            self.origPoint = [self GetGesture:pinch LocationInNode:self.Board];
            self.lastScale = pinch.scale;
        } break;

        case UIGestureRecognizerStateChanged:
        {
            CGPoint pinchPoint = [self GetGesture:pinch LocationInNode:self.Board];
            float scale = 1 - (self.lastScale - pinch.scale);

            float newWidth = MAX(kMinSceneWidth, MIN(kMaxSceneWidth, self.size.width / scale));
            float newHeight = MAX(kMinSceneHeight, MIN(kMaxSceneHeight, self.size.height / scale));

            [self.gameScene setSize:CGSizeMake(newWidth, newHeight)];                
            self.lastScale = pinch.scale;

        } break;

        default: break;
    }
}

What comes to the problem of panning accidentally dragging your LetterNodes, I usually implement a single TouchDispatcher (usually in GameScene class) that registers all the touches. TouchDispatcher then decides which node(s) should respond to the touch (and in which order).

Problem

Original source

Related problems

• SKNode scale from the touched point