Optimizing 2d tile collision found on Ray Wenderlich (objective-c) - ios

Question

I've been building a platformer game with sprite kit, and I've ran into an issue when attempting to change the size of my player spritenode to better match the art. I am using this algorithm from a Ray Weinderlich tutorial in conjunction with JSTileMap.
- (void)checkForAndResolveCollisionsForPlayer:(Player *)player forLayer:(TMXLayer *)layer
{
NSInteger indices[8] = {7, 1, 3, 5, 0, 2, 6, 8};
player.onGround = NO; ////Here
for (NSUInteger i = 0; i < 8; i++) {
NSInteger tileIndex = indices[i];
CGRect playerRect = [player collisionBoundingBox];
CGPoint playerCoord = [layer coordForPoint:player.desiredPosition];
NSInteger tileColumn = tileIndex % 3;
NSInteger tileRow = tileIndex / 3;
CGPoint tileCoord = CGPointMake(playerCoord.x + (tileColumn - 1), playerCoord.y + (tileRow - 1));
NSInteger gid = [self tileGIDAtTileCoord:tileCoord forLayer:layer];
if (gid != 0) {
CGRect tileRect = [self tileRectFromTileCoords:tileCoord];
//NSLog(#"GID %ld, Tile Coord %#, Tile Rect %#, player rect %#", (long)gid, NSStringFromCGPoint(tileCoord), NSStringFromCGRect(tileRect), NSStringFromCGRect(playerRect));
//1
if (CGRectIntersectsRect(playerRect, tileRect)) {
CGRect intersection = CGRectIntersection(playerRect, tileRect);
//2
if (tileIndex == 7) {
//tile is directly below Koala
player.desiredPosition = CGPointMake(player.desiredPosition.x, player.desiredPosition.y + intersection.size.height);
player.velocity = CGPointMake(player.velocity.x, 0.0); ////Here
player.onGround = YES; ////Here
} else if (tileIndex == 1) {
//tile is directly above Koala
player.desiredPosition = CGPointMake(player.desiredPosition.x, player.desiredPosition.y - intersection.size.height);
} else if (tileIndex == 3) {
//tile is left of Koala
player.desiredPosition = CGPointMake(player.desiredPosition.x + intersection.size.width, player.desiredPosition.y);
} else if (tileIndex == 5) {
//tile is right of Koala
player.desiredPosition = CGPointMake(player.desiredPosition.x - intersection.size.width, player.desiredPosition.y);
//3
} else {
if (intersection.size.width > intersection.size.height) {
//tile is diagonal, but resolving collision vertically
//4
player.velocity = CGPointMake(player.velocity.x, 0.0); ////Here
float intersectionHeight;
if (tileIndex > 4) {
intersectionHeight = intersection.size.height;
player.onGround = YES; ////Here
} else {
intersectionHeight = -intersection.size.height;
}
player.desiredPosition = CGPointMake(player.desiredPosition.x, player.desiredPosition.y + intersection.size.height );
} else {
//tile is diagonal, but resolving horizontally
float intersectionWidth;
if (tileIndex == 6 || tileIndex == 0) {
intersectionWidth = intersection.size.width;
} else {
intersectionWidth = -intersection.size.width;
}
//5
player.desiredPosition = CGPointMake(player.desiredPosition.x + intersectionWidth, player.desiredPosition.y);
}
}
}
}
}
//6
player.position = player.desiredPosition;
}
I am just wondering if there is a more efficient way, or a different algorithm to handle tile collisions of this nature (contact with tiles surrounding the player) that will take into account if my player's sprite is resized to be larger. As it is, if I resize my sprite to be taller than two tile heights or two tile widths, since the tiles are 16px by 16px, it causes the entire tile collision to break down due to it using a 3 by 3 grid to handle tile collisions. My goal is to be able to handle tile collisions without having to add physicsbodies to every "wall" tile, and have the algorithm function independently of the players size. Or at least be able to choose the option with the least performance overhead. I've been thinking and researching tile collision for a few weeks and those are the only two options I have seen function. Thank you everyone for the input in advance, please let me know if any more information is necessary.