SpriteKit - Scale in one direction - ios

Question

How do I make an object grow in one direction is SpriteKit?
Ultimately, I would like to have a node be inserted where the user touches and have each end of a line scale until it hits another object in the same category or hits the edge of the screen. I understand how to have it scale on an axis and I can then cancel the scaling after one collision is detected but I want both directions to scale independently until a collision is made for each. I am new to SpriteKit so my searches may be using the wrong terms but I have not been able to find anything relevant.
Code to add a "wall" where the user touches
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch * touch in touches) {
CGPoint location = [touch locationInNode:self];
[self addWallAtLocation:location];
}
}
-(void)addWallAtLocation:(CGPoint)location{
int odd_or_even = arc4random() % 2;
SKSpriteNode * wall = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(2, 2)];
wall.position = location;
wall.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(2, 2)];
wall.physicsBody.dynamic = NO;
wall.physicsBody.categoryBitMask = wallCategory;
wall.physicsBody.contactTestBitMask = ballCategory;
[self addChild:wall];
SKAction * grow;
if (odd_or_even == 1) {
grow = [SKAction scaleYTo:300 duration:2];
} else {
grow = [SKAction scaleXTo:300 duration:2];
}
[wall runAction:grow];
}
How I want it to work:
Touch 1 makes the horizontal line from a point which shoots out in both directions on the x-axis until both ends hit the edge of the screen. Touch 2 would then create a point which shoots out in both directions on the y-axis until the lower end hits the wall created by Touch 1 and the upper end hits the edge of the screen. The lines (scaled points) are generated where the user touches. So I do not want the part of the vertical line that is highlighted by the red box to be there.
Scaling in one direction is just a solution I see to this problem, if there is a better way of going about it I will certainly try that other solution.

Answer 1

EDIT FOR UPDATED QUESTION:
It sounds like you might be asking "how to scale a thing in a single axis, but then stop the scaling of that single axis in one direction only when it collides with another thing"? There isn't a simple way to do that just using actions, but you you could do some slight of hand by manipulating the anchor point of a sprite. Or, probably more appropriately, you should use 2 sprites per touch, with one action sending one north, and another action sending the other one south. Maybe like this:
-(void)someMethod{
SKSpriteNode *touch2TopPart = [SKSpriteNode node];
SKSpriteNode *touch2BottomPart = [SKSpriteNode node];
touch2TopPart.anchorPoint = CGPointMake(.5, 0);
touch2BottomPart.anchorPoint = CGPointMake(.5, 1);
touch2TopPart.name = #"touch2TopPart";
touch2BottomPart.name = #"touch2BottomPart";
SKAction *sendTopPartUp = [SKAction scaleYTo:100 duration:2];
SKAction *sendBottomPartDown = [SKAction scaleYTo:100 duration:2];
[touch2TopPart runAction:sendTopPartUp withKey:#"sendTopPartUp"];
[touch2BottomPart runAction:sendBottomPartDown withKey:#"sendBottomPartDown"];
}
-(void)whateverTheCollisonMethodIsCalledBetweenThingAandThingB
{
SKSpriteNode *somePartMovingInASingleDirection = thingAOrWhatever;
[somePartMovingInASingleDirection removeAllActions];
}
---ORIGINAL ANSWER
I'm not exactly sure what you're asking, but you already have the actions for scaling in just X or Y, so here's the simple usage for removing one of those actions after physics is simulated. You might be looking for how to detect a specific collision between two entities, but I can't be sure.
-(void)someMethod{
SKSpriteNode *thisSprite = [SKSpriteNode node];
thisSprite.name = #"spriteRunningActions";
SKAction *growX = [SKAction scaleXTo:100 duration:2];
SKAction *growY = [SKAction scaleYTo:100 duration:2];
[thisSprite runAction:growX withKey:#"actionCurrentlyScalingX"];
[thisSprite runAction:growY withKey:#"actionCurrentlyScalingY"];
}
-(void)didSimulatePhysics
{
SKSpriteNode *thatSprite = (SKSpriteNode*)[self childNodeWithName:#"spriteRunningActions"];
//stop a given action
[thatSprite removeActionForKey:#"actionCurrentScalingX"];
[thatSprite removeActionForKey:#"actionCurrentScalingY"];
}

Answer 2

Setting the anchor point like below made the "lines" scale in one direction.
wall.anchorPoint = CGPointMake(0, 0);