spritekit SKAction.resizeToHeight is not repeating - ios

Question

I want to increase the height of in touch events, it's same like stick hero is doing. I am trying following code
func changeHeight(){
let action = SKAction.resizeToHeight(self.leadherNode!.size.height+50, duration: 0.5);
let seq = SKAction.repeatActionForever(action)
self.leadherNode?.runAction(seq, withKey: "height")
}
but unfortunately it just increase the height of node for first time and it never repeats. How can I achieve this?

Answer 1

Changes to an argument of an SKAction after it has started will have no effect on the action. You will need to create a new action with the updated value at each step. Here's one way to do that:
Define and initialize the height and max height properties
var spriteHeight:CGFloat = 50.0;
let maxHeight:CGFloat = 500.0
Call this from didMoveToView
resizeToHeight()
This function creates an SKAction that resizes a sprite to a specific height. After the completion of the action, the function updates the height value and then calls itself.
func resizeToHeight() {
self.leadherNode?.runAction(
SKAction.resizeToHeight(self.spriteHeight, duration: 0.5),
completion:{
// Run only after the previous action has completed
self.spriteHeight += 50.0
if (self.spriteHeight <= self.maxHeight) {
self.resizeToHeight()
}
}
)
}

Answer 2

I dont know swift. But I can write objective-c version.
CGFloat currentSpriteSize;//Create private float
SKSpriteNode *sprite;//Create private sprite
currentSpriteSize = sprite.size.height;//Into your start method
//And your Action
SKAction *seq = [SKAction sequence:#[[SKAction runBlock:^{
currentSpriteSize += 50;
}], [SKAction resizeToHeight:currentSpriteSize duration:0.5]]];
[sprite runAction:[SKAction repeatActionForever:seq]];