Change sprite image on touch - ios

Question

I am making a game which purpose it is to catch multiple objects that are falling from the top of the screen. In the bottom there is a basket to catch the objects. i managed to randomly spawn objects from the top dropping to the bottom using raywenderlich's tutorial : http://www.raywenderlich.com/42699/spritekit-tutorial-for-beginners
But what i want is that when i tap on that random object, the image of that object changes into another image , so just for imagination if the random objects are cats, after i tap them they have to become dogs, how do i have to program this?
edit this is what i got so far :
#import "MyScene.h"
static NSString* basketCategoryName = #"basket";
static NSString* monsterCategoryName= #"monster";
static const uint32_t projectileCategory = 0x1 << 0;
static const uint32_t monsterCategory = 0x1 << 1;
#interface MyScene() <SKPhysicsContactDelegate>
#property (nonatomic) SKLabelNode * scoreLabelNode;
#property int score;
#property (nonatomic) SKSpriteNode * basket;
#property (nonatomic) SKSpriteNode * monster;
#property (nonatomic) BOOL isFingerOnBasket;
#property (nonatomic) BOOL isFingerOnMonster;
#property (nonatomic) BOOL isTouching;
#property (nonatomic) NSTimeInterval lastSpawnTimeInterval;
#property (nonatomic) NSTimeInterval lastUpdateTimeInterval;
//#property (nonatomic, strong) SKSpriteNode *selectedNode;
#end
#implementation MyScene
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
// Initialize label and create a label which holds the score
_score = 0;
_scoreLabelNode = [SKLabelNode labelNodeWithFontNamed:#"MarkerFelt-Wide"];
_scoreLabelNode.position = CGPointMake( CGRectGetMidX( self.frame ), 3 * self.frame.size.height / 4 );
_scoreLabelNode.zPosition = 100;
_scoreLabelNode.text = [NSString stringWithFormat:#"%d", _score];
[self addChild:_scoreLabelNode];
// Set the background
SKTexture* groundTexture = [SKTexture textureWithImageNamed:#"AcornFlipTestBackground1136x640.png"];
groundTexture.filteringMode = SKTextureFilteringNearest;
for( int i = 0; i < 2 + self.frame.size.width / ( groundTexture.size.width * 2 ); ++i ) {
SKSpriteNode* sprite = [SKSpriteNode spriteNodeWithTexture:groundTexture];
[sprite setScale:1.0];
sprite.size = CGSizeMake(self.frame.size.width,self.frame.size.height);
sprite.position = CGPointMake(CGRectGetMidX(self.frame),
CGRectGetMidY(self.frame));
[self addChild:sprite];
}
// Make grafity for sprite
self.physicsWorld.gravity = CGVectorMake(0.0f, 0.0f);
self.physicsWorld.contactDelegate = self;
// Make catching object sprite
self.basket = [SKSpriteNode spriteNodeWithImageNamed:#"bedTest.png"];
self.basket.position = CGPointMake(CGRectGetMidX(self.frame), _basket.frame.size.height * 0.5f);
self.basket.name = basketCategoryName;
[self addChild:self.basket];
// For default this is set to no until user touches the basket and the game begins.
self.isTouching = NO;
}
return self;
}
-(void)addAcorn{
if(_isTouching == YES) {
self.monster= [SKSpriteNode spriteNodeWithImageNamed:#"AcornFinal.png"];
// Determine where to spawn the monster along the X axis
int minX = self.monster.size.width;
int maxX = self.frame.size.width - self.monster.size.width;
int rangeX = maxX - minX;
int actualX = (arc4random() % rangeX)+minX;
// Random position along the X axis as calculated above
// This describe from which way the acorns move
// - means moving from top to the right and + means moving from the top to the left
self.monster.position = CGPointMake(actualX ,self.frame.size.height+ self.monster.size.height);
self.monster.name = monsterCategoryName;
[self addChild:self.monster];
CGSize contactSize = CGSizeMake(self.monster.size.width - 5.0, self.monster.size.height - 10.0);
self.monster.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:contactSize]; // 1
self.monster.physicsBody.dynamic = YES; // 2
self.monster.physicsBody.categoryBitMask = monsterCategory; // 3
self.monster.physicsBody.contactTestBitMask = projectileCategory; // 4
self.monster.physicsBody.collisionBitMask = 0; // 5
// Determine speed of the monster
int minDuration = 8.0;
int maxDuration = 10.0;
int rangeDuration = maxDuration - minDuration;
int actualDuration = (arc4random() % rangeDuration) + minDuration;
// Create the actions
SKAction * actionMove = [SKAction moveTo:CGPointMake(actualX,-self.monster.size.height) duration:actualDuration];
SKAction * actionMoveDone = [SKAction removeFromParent];
[self.monster runAction:[SKAction sequence:#[actionMove, actionMoveDone]]];
}
}
- (void)updateWithTimeSinceLastUpdate:(CFTimeInterval)timeSinceLast {
self.lastSpawnTimeInterval += timeSinceLast;
if (self.lastSpawnTimeInterval > 0.5) {
self.lastSpawnTimeInterval = 0;
[self addAcorn];
}
}
- (void)update:(NSTimeInterval)currentTime {
// Handle time delta.
// If we drop below 60fps, we still want everything to move the same distance.
CFTimeInterval timeSinceLast = currentTime - self.lastUpdateTimeInterval;
self.lastUpdateTimeInterval = currentTime;
if (timeSinceLast > 1) { // more than a second since last update
timeSinceLast = 1.0 / 60.0;
self.lastUpdateTimeInterval = currentTime;
}
[self updateWithTimeSinceLastUpdate:timeSinceLast];
}
-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
self.isTouching = YES;
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
SKNode* body = [self nodeAtPoint:location];
if ([body.name isEqualToString:basketCategoryName])
{
NSLog(#"Began touch on basket");
self.isFingerOnBasket = YES;
}
else if ([body.name isEqualToString:monsterCategoryName])
{
NSLog(#"Began touch on MONSTER");
self.isFingerOnMonster = YES;
}
}
-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
if (self.isFingerOnMonster) {
// 2 Get touch location
UITouch* touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
CGPoint previousLocation = [touch previousLocationInNode:self];
// 3 Get node for paddle
SKSpriteNode* monster = (SKSpriteNode*)[self childNodeWithName: monsterCategoryName];
int oldPosition = monster.position.x + (location.x - previousLocation.x);
self.monster = [SKSpriteNode spriteNodeWithImageNamed:#"AcornFinal.png"];
monster.position = CGPointMake(oldPosition, monster.position.y);
NSLog(#"reached the touch though");
}
// 1 Check whether user tapped paddle
if (self.isFingerOnBasket) {
// 2 Get touch location
UITouch* touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
CGPoint previousLocation = [touch previousLocationInNode:self];
// 3 Get node for paddle
SKSpriteNode* basket = (SKSpriteNode*)[self childNodeWithName: basketCategoryName];
// 4 Calculate new position along x for paddle
int basketX = basket.position.x + (location.x - previousLocation.x);
// 5 Limit x so that the paddle will not leave the screen to left or right
basketX = MAX(basketX, basket.size.width/2);
basketX = MIN(basketX, self.size.width - basket.size.width/2);
// 6 Update position of paddle
basket.position = CGPointMake(basketX, basket.position.y);
CGSize contactSize = CGSizeMake(basket.size.width - 8.0, basket.size.height - 8.0);
basket.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:contactSize];
basket.physicsBody.dynamic = YES;
basket.physicsBody.categoryBitMask = projectileCategory;
basket.physicsBody.contactTestBitMask = monsterCategory;
basket.physicsBody.collisionBitMask = 0;
basket.physicsBody.usesPreciseCollisionDetection = YES;
}
}
- (void)projectile:(SKSpriteNode *)basket didCollideWithMonster:(SKSpriteNode *)monster {
NSLog(#"Hit");
[monster removeFromParent];
}
- (void)didBeginContact:(SKPhysicsContact *)contact
{
// 1
SKPhysicsBody *firstBody, *secondBody;
if (contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask)
{
firstBody = contact.bodyA;
secondBody = contact.bodyB;
}
else
{
firstBody = contact.bodyB;
secondBody = contact.bodyA;
}
// 2
if ((firstBody.categoryBitMask & projectileCategory) != 0 &&
(secondBody.categoryBitMask & monsterCategory) != 0)
{
[self projectile:(SKSpriteNode *) firstBody.node didCollideWithMonster:(SKSpriteNode *) secondBody.node];
NSLog(#"test");
_score++;
_scoreLabelNode.text = [NSString stringWithFormat:#"%d", _score];
}
}
// Removing this void will result in being able to drag the basket accross the screen without touching the basket itself.
-(void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
self.isFingerOnBasket = NO;
self.isFingerOnMonster = NO;
}
#end

Answer 1

Once a touch is detected on a sprite (I assume you already got that working out) you can either create the sprite again with spriteNodeWithImageNamed. Make sure you save the previous node's position and set it again on the new sprite so it will match the position of the old sprite.
CGPoint oldPosition = touchedSprite.position;
touchedSprite = [SKSpritNode spriteWithImageNamed:#"imgge.png"];
touchedSprite.position = oldPosition;
// If you have any other sprite properties you will have to save them as well
You can also set the texture with setTexture method which will not require you to change anything else (e.g. position) :
[touchedSprite setTexture:[SKTexture textureWithImageNamed:#"image.png"]];
EDIT :
Answering your question in the comments you implement this in the touchesEnded method of the parent node of the sprites :
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInNode:self];
for (SKSpriteNode *sprite in fallingSprites) { // Assuming fallingSprite is an array containing the cat sprites you want to detect touches for
if (CGRectContainsPoint(sprite.frame, touchLocation)) {
[sprite setTexture:[SKTexture textureWithImageNamed:#"dog.png"]];
}
}
}
Another approach (Haven't tried it yet) is to subclass SKSpriteNode and implement the same method but without the touch detection in rect since if this method is called the sprite has been touched .

Answer 2

Each part of the skeleton model is a spritekit node. Find the node that you wish to change and update its texture property like this:
spriteKitNode.texture = // Updated SKTexture

Answer 3

In your TouchesEnded event:
Add a small skspritenode positioned at the touch location with a small physics body that last for a short duration. ("touch spritenode)
Set up contact between all possible transformed objects and the "touch spritenode"
Create a subclass of SKSpritenode for the falling objects that has a variable to stores their type.
In the method called from contact between the touch spritenode and the falling objects:
Remove the touchspritenode first
Create if statements to check which falling object was touched.
Update the image of the contacted falling object spritenode according to its type.
If you are following Raywenderlich you have access to the actual syntax