How do I implement enemies that shoot? - objective-c

Question

I made a game with SpriteKit. I structured my game by coding a GameScene (SKScene) and a separate enemy class.
I want the spawning enemies to shoot a particle e.g. every 2 seconds (just moving an SKEmitterNode by the y axis) I tried to do it with a timer, but it doesn't really work.
I call my Enemy class from the gaming Scene with this code:
GameScene.m
-(void)enemiesLevel1{
EnemyClass* wave1 = [[EnemyClass alloc] init];
[wave1 enemiesLevel1:self];
}
And I am basically calling this method from EnemyClass.m
-(void)enemiesLevel1:(SKScene *)scene
{
enemy = [SKSpriteNode spriteNodeWithImageNamed:Enemy];
//Enemy Path
(...)
SKAction *followPath2 = [SKAction followPath:pathRef2
asOffset:NO
orientToPath:YES
duration: pathSpeed];
SKAction *forever = [SKAction repeatActionForever:followPath2];
//PhysicsBody Eigenshaften
enemy.physicsBody =[SKPhysicsBody bodyWithCircleOfRadius:enemy.size.width];
enemy.physicsBody.dynamic = YES;
enemy.physicsBody.categoryBitMask = enemyCategory;
[enemy runAction:forever];
[scene addChild:enemy];
NSTimer *timer;
timer = [NSTimer scheduledTimerWithTimeInterval:0.5
target:self
selector:#selector(weaponParticle)
userInfo:nil
repeats:YES];
}
-(void)weaponParticle{
screenHeight = self.frame.size.height;
screenWidth = self.frame.size.width;
//Schuss-Particles
enemyParticlePath = [[NSBundle mainBundle] pathForResource:#"ShootFire" ofType:#"sks"];
enemyParticle = [NSKeyedUnarchiver unarchiveObjectWithFile:enemyParticlePath];
enemyParticle.physicsBody =[SKPhysicsBody bodyWithCircleOfRadius:0.2];
enemyParticle.physicsBody.categoryBitMask = shootCategory;
enemyParticle.physicsBody.contactTestBitMask = playerCategory;
//Schuss-Action
moveDown = [SKAction moveByX:0.0 y:-screenHeight duration:1.0];
remove = [SKAction removeFromParent];
weaponShot = [SKAction sequence:#[moveDown, remove]];
enemyParticle.position = CGPointMake(enemy.position.x, enemy.position.y+10);
[self addChild:enemyParticle];
[enemyParticle runAction: weaponShot];
}
The enemies are spawning 1 by 1 just how I wanted, but they can't shoot. Can anyone help me out?

Answer 1

Instead of scheduling NSTimer try something like this:
SKAction *shoot = [SKAction runBlock:^{
// add code that shoots here
}];
SKAction *wait = [SKAction waitForDuration:0.5];
[enemy runAction:[SKAction repeatActionForever:[SKAction sequence:#[shoot, wait]]]];