Animate masked image in SpriteKit (SKCropNode) - animation

Question

I'm using Sprite Kit to create my first iOS app, and I'm stumbling over what seems to be a pretty basic problem.
I'm trying to animate the contents (fillNode) of a SKCropNode (cropNode). The code below sets up the SKScene just fine (I see the illustration masked correctly, placed over the background image in the right location)...
SKSpriteNode *logoBG = [[SKSpriteNode alloc] initWithImageNamed:logoBackground];
logoBG.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
[self addChild:logoBG];
SKCropNode *cropNode = [[SKCropNode alloc] init];
cropNode.maskNode = [[SKSpriteNode alloc] initWithImageNamed:logoMask];
SKSpriteNode *fillNode = [[SKSpriteNode alloc] initWithImageNamed:logoImage];
[cropNode addChild:fillNode];
fillNode.position = CGPointMake(0,300);
cropNode.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
self.logoContent = cropNode;
[self addChild:self.logoContent];
...but I can't access the masked illustration to animate its position (I want it to start off outside the mask and slide into position):
CGRect screenBound = [[UIScreen mainScreen] bounds];
CGSize screenSize = screenBound.size;
SKAction *moveUp = [SKAction moveByX: 0 y: 100 duration: 5];
SKAction *moveSequence = [SKAction sequence:#[moveUp]];
[self.logoContent.target_illustration runAction: moveSequence completion:^{ // '.target_illustration' = the SKSpriteNode that I want to animate; cropNode.fillNode
SKScene *titleScreen = [[TitleScreen alloc] initWithSize:self.size];
SKTransition *fade = [SKTransition fadeWithDuration:(1)];
[self.view presentScene:titleScreen transition:fade];
}];
I can only animate the whole logoContent rather than its child nodes.
Any ideas where I'm going wrong?

Answer 1

Just for reference if anyone wants to know how to mask, here is a simple snippet
- (void) cropNodes
{
// the parent node i will add to screen
SKSpriteNode *picFrame = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(100, 100)];
picFrame.position = CGPointMake(200, 200);
// the part I want to run action on
SKSpriteNode *pic = [SKSpriteNode spriteNodeWithImageNamed:#"Spaceship"];
pic.name = #"PictureNode";
SKSpriteNode *mask = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:CGSizeMake(80, 50)];
SKCropNode *cropNode = [SKCropNode node];
[cropNode addChild:pic];
[cropNode setMaskNode:mask];
[picFrame addChild:cropNode];
[self addChild:picFrame];
// run action in this scope
//[pic runAction:[SKAction moveBy:CGVectorMake(30, 30) duration:10]];
// outside scope - pass its parent
[self moveTheThing:cropNode];
}
- (void) moveTheThing:(SKNode *) theParent
{
// the child i want to move
SKSpriteNode *moveThisThing = (SKSpriteNode *)[theParent childNodeWithName:#"PictureNode"];
[moveThisThing runAction:[SKAction moveBy:CGVectorMake(30, 30) duration:10]];
}

Answer 2

Got it!
[self.logoContent.target_illustration runAction: moveSequence completion:^{
should be
[self.logoContent.children[0] runAction: moveSequence completion:^{
My illustration now moves as directed :)