Endless Action with SKActions Objective C

Question

I am building a game with sprite kit and have a sprite moving from left to right with an endless action.

SKAction *moveRight = [SKAction moveByX:3.0 y:0 duration:3.5];
SKAction *moveLeft = [SKAction moveByX:-3.0 y:0 duration:3.5];
SKAction *reversedMoveRight = [moveRight reversedAction];
SKAction *reversedMoveLeft = [moveLeft reversedAction];

SKAction *completion = [SKAction runBlock:^{

    SKAction *sequence = [SKAction sequence:@[moveRight, moveLeft, reversedMoveRight,reversedMoveLeft]];
    SKAction *endlessAction = [SKAction repeatActionForever:sequence];
    [snake runAction:endlessAction];
}];

[snake runAction:completion withKey:@"KeySnake"];

This works, but after a short period of time my game slows down. The CPU and memory usage continues to grow in the debug navigator in Xcode. I think the endless action is causing the problem, but I don't know any other way to move it constantly like I want to.

Answer 1

From your comment I understand you are calling

[snake runAction:completion withKey:@"KeySnake"];

inside the update method. This is the problem, infact you are creating and running a new action every frame.

Move the whole block of code (you showed in your question) inside a method that is called only once.

Example: here I also refactored the construction of your action and changed the x value (in the action) from 3.0 to 100.0

#import "GameScene.h"

@implementation GameScene
{
    SKSpriteNode * _snake;
}

- (void)didMoveToView:(SKView *)view {
    [self addSnake];
    [self startSnakeMoving];
}

- (void)addSnake{
    _snake = [SKSpriteNode spriteNodeWithImageNamed:@"Snake"];
    _snake.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
    [self addChild:_snake];
}

- (void)startSnakeMoving {
    SKAction * moveRight = [SKAction moveByX:100.0 y:0 duration:3.5];
    SKAction * sequence = [SKAction sequence:@[moveRight, moveRight.reversedAction, moveRight.reversedAction, moveRight]];
    SKAction * endlessAction = [SKAction repeatActionForever:sequence];
    [_snake runAction:endlessAction withKey:@"KeySnake"];
}
@end