Continually repeat an action

Question

I want my action to repeat every 2 seconds. Here is my current code:

    SKSpriteNode *lightnut = [SKSpriteNode spriteNodeWithImageNamed:@"lightnut.png"];
    BOOL heads = arc4random_uniform(100) < 50;
    lightnut.position = (heads)? CGPointMake(257,510) : CGPointMake(50,510);
    [self addChild: lightnut];

    SKAction *moveNodeUp = [SKAction moveByX:0.0 y:-600.0 duration:2.0];
    [lightnut runAction: moveNodeUp];

How would I repeat the action that is being said in the code above over and over again? I want the sprite to start moving, wait 2 seconds, and then start another one. Is it possible to send another sprite before the original sprite has finished moving to the next spot?

Thank you!

Answer 1

I suggest you use an SKAction to generate the sprites since actions pause/resume appropriately when you pause/resume the scene or view. Here's an example of how to do that:

// Declare SKAction that waits 2 seconds
SKAction *wait = [SKAction waitForDuration:2.0];    

// Declare SKAction block to generate the sprites
SKAction *createSpriteBlock = [SKAction runBlock:^{
    SKSpriteNode *lightnut = [SKSpriteNode spriteNodeWithImageNamed:@"lightnut.png"];
    BOOL heads = arc4random_uniform(100) < 50;
    lightnut.position = (heads)? CGPointMake(257,510) : CGPointMake(50,510);
    [self addChild: lightnut];

    SKAction *moveNodeUp = [SKAction moveByX:0.0 y:-600.0 duration:2.0];
    [lightnut runAction: moveNodeUp];
}];

// Combine the actions
SKAction *waitThenRunBlock = [SKAction sequence:@[wait,createSpriteBlock]];

// Lather, rinse, repeat
[self runAction:[SKAction repeatActionForever:waitThenRunBlock]];