Efficient SpriteKit Spatial Hashing Collision Detection For 2D Game - ios

Question

I've been looking around for tutorials on spatial hashing for Objective C or spriteKit. I've found examples in other languages, but I can't Seem to figure it out. I've gotten this far but I'm stuck.
This Loads Enemy Sprites To An NSMutableDictionary, I divide Their x,y positions by 64 to get their cellID (I use cellID as a key for the enemy in NSMutableDictionary).
- (void)loadEnemies {
TMXObjectGroup *enemiesGroup = [self.map groupNamed:#"enemies"];
for (NSDictionary *enemyDict in enemiesGroup.objects) {
NSString *enemyType = enemyDict[#"type"];
NSString *firstFrameName =
[NSString stringWithFormat:#"%#1.png",enemyType];
CGPoint enemyPosition =
CGPointMake([enemyDict[#"x"] floatValue], [enemyDict[#"y"] floatValue]);
CGPoint cellNumber =
CGPointMake(enemyPosition.x / 64, enemyPosition.y / 64);
NSString *CellID =
[NSString stringWithFormat:#"%#",NSStringFromCGPoint(cellNumber)];
SMCEnemy *enemy = [[NSClassFromString(enemyType)alloc]
initEnemyWithImageNamed:firstFrameName Position:enemyPosition];
enemy.position = enemyPosition;
enemy.player = self.cat;
enemy.map = self.map;
enemy.delegate = self;
[self.map addChild:enemy];
enemy.zPosition = 900;
//enemies added to NSMutableDictionary
[self.enemeyDictionary setObject:enemy forKey:CellID];
}
}
Ive added enemies to an NSMutableDictionary using CellID as a key.
This Checks For Collisions with the player, I first check the distance between the player and each enemy; if the distance is less than 1000, then enemy becomes active.
- (void)checkForEnemyCollisions:(SMCEnemy *)enemy {
CGFloat distance = CGPointDistance(enemy.posiiton, self.player.position);
if (distance < 1000){
enemy.isActive = YES;
} else {
enemy.isActive = NO;
}
if (enemy.isActive && enemy.life > 0) {
//cat hurt
if ((CGRectIntersectsRect(self.cat.collisionBoundingBox, enemy.collisionBoundingBox) || CGRectIntersectsRect(self.cat.collisionBoundingBox, enemy.attackBox)) && self.cat.isActive && !enemy.hidden && enemy.canHurtPlayer){
enemy.attackBox = CGRectNull;
if (enemy.position.x < self.cat.position.x) {
[self.cat bounceWithDirection:1];
}else{
[self.cat bounceWithDirection:-1];
}
[self.cat tookHit:self.cat];
[self movementCoolDownForCharacter:self.cat coolDownTime:.5];
}
// enemy hurt
if (CGRectIntersectsRect(enemy.collisionBoundingBox, self.cat.attackBox)&& !enemy.isHurt && enemy.isStun && !enemy.hidden) {
CGRect intersection = CGRectIntersection(enemy.collisionBoundingBox,self.cat.attackBox);
_hit.position = CGPointMake(intersection.origin.x, intersection.origin.y);
_hit.hidden = NO;
SKAction *DoneAction = [SKAction runBlock:(dispatch_block_t)^() {
_hit.hidden = YES;
}];
SKAction *moveLaserActionWithDone = [SKAction sequence:#[enemy.hitAnim,DoneAction]];
[_hit runAction:moveLaserActionWithDone];
enemy.isHurt = YES;
[enemy tookHit:self.cat];
[self movementCoolDownForCharacter:enemy coolDownTime:.5];
}
}
The Update Method
- (void)update:(NSTimeInterval)currentTime {
NSTimeInterval delta = currentTime - self.previousUpdateTime;
self.previousUpdateTime = currentTime;
if (delta > 0.1) {
delta = 0.1;
}
for (SMCEnemy *enemy in self.enemies) {
[self checkForEnemyCollisions:enemy];
}
}
I want to use spatial hashing instead of going through every enemy item in the enemyArray to improve performance.
Im stuck Any Help would be really awesome! :D