UIPinchGestureRecognizer trouble - objective-c

Question

Ok, i've read a few posts on this one (ex. UIImageView Gestures (Zoom, Rotate) Question) but I can't seem to fix my problem.
I have the following setup: an SKScene, an SKNode _backgroundLayer and 9 SKSpriteNodes that are tiles that make up the background and are attached to the _backgroundLayer.
Since these 9 tiles make a 3x3 square and they are quite large, I need to be able to zoom in and look at other SKSpriteNodes that will be on top of these 9 background images.
There are two problems:
1) When I pinch to zoom in or zoom out it seems like it is zooming in/out from location (0,0) of the _backgroundLayer and not from the touch location.
2) I have added some bounds so that the user can not scroll out of the 9 background images. In general it works. However, if I zoom in then move towards the top of the 9 background images and then zoom out the bounding conditions go berserk and the user can see the black space outside the background images. I need a way to limit the amount of zooming out that the user can do depending on where he's at.
Any ideas? Thanks!
I include my code below:
#import "LevelSelectScene.h"
#import "TurtleWorldSubScene.h"
#interface LevelSelectScene ()
#property (nonatomic, strong) SKNode *selectedNode;
#end
#implementation LevelSelectScene
{
SKNode *_backgroundLayer;
}
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
/* Setup your scene here */
_backgroundLayer = [SKNode node];
_backgroundLayer.name = #"backgroundLayer";
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
[_backgroundLayer setScale:0.76];
} else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone && IS_WIDESCREEN) {
} else {
[_backgroundLayer setScale:0.36];
}
[self addChild:_backgroundLayer];
SKTexture *backgroundTexture = [SKTexture textureWithImageNamed:#"levelSelect"];
int textureID = 0;
for (int i = 0; i<3; i++) {
for (int j = 0; j<3; j++) {
SKSpriteNode *background = [SKSpriteNode spriteNodeWithTexture:backgroundTexture];
background.anchorPoint = CGPointZero;
background.position = CGPointMake((background.size.width)*i, (background.size.height)*j);
background.zPosition = 0;
background.name = [NSString stringWithFormat:#"background%d", textureID];
textureID++;
[_backgroundLayer addChild:background];
}
}
[TurtleWorldSubScene displayTurtleWorld:self];
}
return self;
}
- (void)didMoveToView:(SKView *)view {
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePanFrom:)];
[[self view] addGestureRecognizer:panGestureRecognizer];
//UITapGestureRecognizer * tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTap:)];
// [self.view addGestureRecognizer:tapRecognizer];
UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(handlePinch:)];
[[self view] addGestureRecognizer:pinchGestureRecognizer];
}
- (void)handlePanFrom:(UIPanGestureRecognizer *)recognizer {
if (recognizer.state == UIGestureRecognizerStateBegan) {
CGPoint touchLocation = [recognizer locationInView:recognizer.view];
touchLocation = [self convertPointFromView:touchLocation];
SKNode *node = [self nodeAtPoint:touchLocation];
_selectedNode = node;
} else if (recognizer.state == UIGestureRecognizerStateChanged) {
CGPoint translation = [recognizer translationInView:recognizer.view];
translation = CGPointMake(translation.x, -translation.y);
CGPoint initialPosition = CGPointAdd(_backgroundLayer.position, translation);
_backgroundLayer.position = [self boundLayerPos:initialPosition];
[recognizer setTranslation:CGPointZero inView:recognizer.view];
} else if (recognizer.state == UIGestureRecognizerStateEnded) {
float scrollDuration = 0.2;
CGPoint velocity = [recognizer velocityInView:recognizer.view];
CGPoint pos = [_backgroundLayer position];
CGPoint p = CGPointMultiplyScalar(velocity, scrollDuration);
CGPoint newPos = CGPointMake(pos.x + p.x, pos.y - p.y);
newPos = [self boundLayerPos:newPos];
[_backgroundLayer removeAllActions];
SKAction *moveTo = [SKAction moveTo:newPos duration:scrollDuration];
[moveTo setTimingMode:SKActionTimingEaseOut];
[_backgroundLayer runAction:moveTo];
}
}
- (void)handlePinch:(UIPinchGestureRecognizer *) recognizer
{
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
if(_backgroundLayer.xScale*recognizer.scale < 0.76) {
//SKSpriteNode *backgroundTile = (SKSpriteNode *)[_backgroundLayer childNodeWithName:#"background0"];
[_backgroundLayer setScale:0.76];
} else if(_backgroundLayer.xScale*recognizer.scale > 2) {
[_backgroundLayer setScale:2.0];
} else {
[_backgroundLayer runAction:[SKAction scaleBy:recognizer.scale duration:0]];
}
} else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone && IS_WIDESCREEN) {
} else {
if(_backgroundLayer.xScale*recognizer.scale < 0.36) {
[_backgroundLayer setScale:0.36];
} else if(_backgroundLayer.xScale*recognizer.scale > 2) {
[_backgroundLayer setScale:2.0];
} else {
[_backgroundLayer runAction:[SKAction scaleBy:recognizer.scale duration:0]];
}
}
recognizer.scale = 1;
}
- (CGPoint)boundLayerPos:(CGPoint)newPos {
SKSpriteNode *backgroundTile = (SKSpriteNode *)[_backgroundLayer childNodeWithName:#"background0"];
CGPoint retval = newPos;
retval.x = MIN(retval.x, 0);
retval.x = MAX(retval.x, -(backgroundTile.size.width*_backgroundLayer.xScale*3)+self.size.width);
retval.y = MIN(retval.y, 0);
retval.y = MAX(retval.y, -(backgroundTile.size.height*_backgroundLayer.xScale*3)+self.size.height);
return retval;
}