Alternative spawning method to a timer - ios

Question

I am making a reaction game with a parallax scrolling ground. My enemy spawning timer is located in the didMoveToView and now comes my problem. The game speeds up while playing, but my spawning method stays the same, so its kind of boring if the enemys are spawned with the same frequency.
Here is the code:
//inside the didMoveToView
SKAction *addEnemRand = [SKAction performSelector:#selector(addRandomEnemy) onTarget:self];
SKAction *addEnemRandWait = [SKAction waitForDuration:2];
SKAction *addEnemRandAll = [SKAction sequence:#[addEnemRandWait, addEnemRand]];
SKAction *addEnemRandAllForever = [SKAction repeatActionForever:addEnemRandAll];
[self runAction:addEnemRandAllForever];
Does someone know a way to spawn the enemys in a proper manner ?
Here is the code for moving the ground (there are two). Maybe its possible to relate the spawning speed with the position of the ground ?:
-(void)addGround:(SKSpriteNode *)sprite withSpeed:(int)speed {
if (ground.position.x+ground.frame.size.width/2 < 0) {
ground.position = CGPointMake(self.size.width+ground.size.width/2, ground.size.height/2+1);
}
// movement
ground.position = CGPointMake(ground.position.x-speed, ground.position.y);
}
Thanks for the help ! (code in objective c please)
EDIT: So it seems GamePlayKit can help me but I have no idea how to implement the spawning method with it. I read some tutorials in the internet but it didn't helped me. Can someone help me ?

Answer 1

I think its worth looking into the randomizing that GamePlayKit provides to do this.
Take a look at this tutorial where you implement a "basic rule system in combination with another random distribution to handle the respawning behaviour of enemies"

Answer 2

You can either manage the spawn time using the ground position, or using the time, since the level has been started. That's my code in update method for simular task, using the time passed.
properties in initWithSize method:
self.lastUpdateTimeInterval = 0;
self.timeSinceEnemyAdded = 0;
self.addEnemyTimeInterval = 1.5;
self.totalGameTime = 0;
Update method:
-(void)update:(NSTimeInterval)currentTime {
if (self.lastUpdateTimeInterval ) {
self.timeSinceEnemyAdded += currentTime - self.lastUpdateTimeInterval;
self.totalGameTime += currentTime - self.lastUpdateTimeInterval;
}
if (self.timeSinceEnemyAdded > self.addEnemyTimeInterval && !self.gameOver) {
[self addEnemy];
self.timeSinceEnemyAdded = 0;
}
self.lastUpdateTimeInterval = currentTime;
if (self.totalGameTime > 480) {
self.addEnemyTimeInterval = 0.5;
self.minSpeed = -160;
} else if (self.totalGameTime > 240) {
self.addEnemyTimeInterval = 0.65;
self.minSpeed = -150;
} else {
//Something else
}
}
You can just manage the ground lenght property, if you want