Can we change dynamically the interval of "schedule"? - iphone

Question

I'm making a game on iPhone using cocos2d, and I have a question.
In my init method I'm doing this :
[self schedule:#selector(newMonster:) interval:1];
It create a new monster every second.
But I'd like that the interval change over time. For example :
The 10 first seconds of the game: a new monster appears every 1 second.
Then for 10 seconds: a new monster appears every 0.8 second.
And after every 0.5 second...
How can I do that?
Thanks !

Answer 1

You may try this- (I have copied some code from #bddckr)
Initial time:
self.monsterSpawnStartDate = [NSDate date];
self.lastTimeScheduledBefore = 0;//new var
Scheduled Method to create monster
- (void)scheduledMethod {
NSTimeInterval seconds = [[NSDate date] timeIntervalSinceDate:monsterSpawnStartDate];
[self newMonster]; // Let a new monster spawn
if (seconds >= 20.0 && lastTimeScheduledBefore == 10){
[self unschedule:#(scheduledMethod)];
[self unschedule:#(scheduledMethod) interval:0.5];
lastTimeScheduledBefore = 20;
}
else if (seconds >= 10.0 && lastTimeScheduledBefore == 0){
[self unschedule:#(scheduledMethod)];
[self unschedule:#(scheduledMethod) interval:0.8]
lastTimeScheduledBefore = 10;
}
}
You can modify it as your need. You can use mod if it goes through a cycle.

Answer 2

Make an instance variable and property of NSDate called monsterSpawnStartDate, make it an retaining property and synthesize it.
As soon as your first monster should be created, set it:
self.monsterSpawnStartDate = [NSDate date]; // Current date and time
And replace your code by this:
[self schedule:#selector(adjustMonsterSpawnRate) interval:0.1]; // Seems like you want it to fire every 0.1 seconds
Implement adjustMonsterSpawnRate like this:
- (void)adjustMonsterSpawnRate {
NSTimeInterval seconds = [[NSDate date] timeIntervalSinceDate:monsterSpawnStartDate];
if (((seconds <= 10.0) && (seconds % 1.0)) || ((seconds <= 20.0) && (seconds % 0.8)) ((seconds > 20.0) && (seconds % 0.5)))
[self newMonster]; // Let a new monster spawn
}

Answer 3

I think a better option would be to use a scheduled function for timing and use accumulated time to trigger the enemy creation as follows
self.time_since_last_monster = 0
[self schedule:#selector(new_monster:) interval:0.3];
-(void) new_monster:(ccTime)dt{
self.time_since_last_monster += dt;
if(self.time_since_last_monster > monster_interval){
self.time_since_last_monster -= monster_interval;
[self create_new_monster];
// at this point based on some condition, you can now change monster_interval
}
}
This would give more flexibility.

Answer 4

I'm pretty dumb, so here's what I'd do:
in the .h set a float
float nextMonsterIn;
then in the body
nextMonsterIn = 1.0;
[self scheduleOnce:#selector(newMonster:) interval:nextMonsterIn];
[self schedule:#selector(kickUpDifficulty:) interval:10];
- (void) newMonster : (ccTime) dt
{
[self scheduleOnce:#selector(newMonster:) interval:nextMonsterIn];
//-----make a monster-----
}
- (void) kickUpDifficulty : (ccTime) dt
{
if(nextMonsterIn == 1.0)
nextMonsterIn = 0.8;
else if(nextMonsterIn == 0.8)
{
nextMonsterIn = 0.5;
[self unschedule:#selector(kickUpDifficulty:)];
}
}
Basically every time I call newMonster i'd recursively re-schedule the newMonster based on my current delay, then I can adjust the delay in a timer or every time a monster is killed or wherever.