Is there a more efficient way to clean up my CCNodes? - objective-c

Question

Is there a more efficient way to clean up my CCNodes? I'm calling this function (and others like it for different game objects), on a timer.
- (void)pulseBullets:(NSMutableArray *)bs targets:(NSArray *)targets {
for (Bullet *b in bs) {
for (QuantumPilot *p in targets) {
if (p.active) {
[p processBullet:b];
if (!p.active) {
[self processKill:p];
}
}
}
}
NSMutableArray *bulletsToErase = [NSMutableArray array];
for (Bullet *b in bs) {
[b pulse];
if ([self bulletOutOfBounds:b]) {
[bulletsToErase addObject:b];
}
}
for (Bullet *b in bulletsToErase) {
[b removeFromParentAndCleanup:YES];
}
[bs removeObjectsInArray:bulletsToErase];
}

Answer 1

Ok, but i make no 'statement' on performance, you will have to measure that for yourself. If you iterate a mutable array in reverse order, it is safe to delete an object during the iteration, because the iterator will not be invalidated by the deletion. So you could get rid altogther of the bullets to erase array like so :
for (Bullet *b in [bs reverseObjectEnumerator]) { // *** do not change iteration order ***
for (QuantumPilot *p in targets) {
if (p.active) {
[p processBullet:b];
if (!p.active) {
[self processKill:p];
}
}
}
[b pulse];
if ([self bulletOutOfBounds:b]) {
[b removeFromParentAndCleanup:YES];
[bs removeObject:b];
}
}
this is simpler , but obfuscates the inherent risk of altering an array content during iteration. You make the call as to whether it is 'cleaner'. Also, maybe the 'cost' of reversing the iterator is higher that what you save, as i said you would have to measure it.