Drag and drop SKSpriteNode with the shape of a oval - ios

Question

I have a scene with one sprite, the image used for the sprites is an oval.
The problem I'm facing is that, whenever I use touchAtPoint it returns the sprite even if the touch occurs at a transparent area of the image.
How can I solve that?
My current code looks like:
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
self.backgroundColor = [SKColor blackColor];
self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithImageNamed:#"Red"];
sprite.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:50.0];
sprite.physicsBody.affectedByGravity = NO;
sprite.physicsBody.usesPreciseCollisionDetection = YES;
[self addChild: sprite];
}
return self;
}
- (void)didMoveToView:(SKView *)view {
UIPanGestureRecognizer *gestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePanFrom:)];
[self.view addGestureRecognizer:gestureRecognizer];
}
- (void)handlePanFrom:(UIPanGestureRecognizer *)recognizer {
if (recognizer.state == UIGestureRecognizerStateBegan) {
CGPoint touchLocation = [recognizer locationInView:recognizer.view];
touchLocation = [self convertPointFromView:touchLocation];
SKNode *touchedNode = (SKNode *)[self nodeAtPoint:touchLocation];
_selectedNode = touchedNode;
}
else if (recognizer.state == UIGestureRecognizerStateChanged) {
CGPoint translation = [recognizer translationInView:recognizer.view];
translation = CGPointMake(translation.x, -translation.y);
[self panForTranslation:translation];
[recognizer setTranslation:CGPointZero inView:recognizer.view];
}
}
- (void)panForTranslation:(CGPoint)translation {
CGPoint position = [_selectedNode position];
[_selectedNode setPosition:CGPointMake(position.x + translation.x, position.y + translation.y)];
}

Answer 1

OK, so the only relevant code here is...
CGPoint touchLocation = [recognizer locationInView:recognizer.view];
touchLocation = [self convertPointFromView:touchLocation];
SKNode *touchedNode = (SKNode *)[self nodeAtPoint:touchLocation];
_selectedNode = touchedNode;
This needs to change to something like this...
CGPoint touchLocation = [recognizer locationInView:recognizer.view];
touchLocation = [self convertPointFromView:touchLocation];
SKNode *touchedNode = (SKNode *)[self nodeAtPoint:touchLocation];
// Work out if the touch is inside the circle
CGPoint centerOfNode = CGPointMake(touchedNode.position.x + touchedNode.size.width * 0.5, touchedNode.positiony + touchedNode.size.height * 0.5);
CGFloat dx = touchedNode.position.x - touchLocation.x;
CGFloat dy = touchedNode.position.y - touchLocation.y;
CGFloat distanceFromCenter = sqrtf(dx * dx + dy * dy);
if (distanceFromCenter <= touchedNode.size.width * 0.5) {
_selectedNode = touchedNode;
}