Change image when collision Detected in swift? - ios

Question

i am making a simple game as a project and need to change my 'bird image' when it collides with another 'image'
Now i have the collision detection all set up i just need to change the texture of my 'bird image' to my new image
any tips on how to do this? I'm new to programming thought it would be easy but evidently not...
i have tried changing
var birdTexture = SKTexture(imageNamed: "bird_img_1.png") // global variable
to
birdTexture = SKTexture(imageNamed: "bird_img_dead.png") // this is inside collision detection
GameScene Class:-
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var bg = SKSpriteNode() // Create Background
var bird = SKSpriteNode() // Create User Bird
var scoreLabel = SKLabelNode() // Create Score Label
var score: Int = 0 // Create Score Integer
var enemyBird = SKSpriteNode() // Create Enemy Bird
var birdGroup:UInt32 = 1 // Bird Collision Group
var objectGroup:UInt32 = 2 // Enemy Collision Group
var scoreGroup:UInt32 = 3 // Score Collision Group
var gameOver = 0 // Game Over function
var movingObjects = SKNode() // ??
var scoreTimer = NSTimer() // Create Score Timer
var gameOverLabel = SKLabelNode() // Game over label
var labelHolder = SKSpriteNode() // Holds Label - Game Over
var enemySpawnTimer = NSTimer() // Starts Enemy Spawner
var Menu = 0
/* Put Bird in and animate */
var birdTexture = SKTexture(imageNamed: "bird_img_1.png")
var birdTexture2 = SKTexture(imageNamed: "bird_img_2.png")
var birdTexture3 = SKTexture(imageNamed: "bird_img_3.png")
var birdTexture4 = SKTexture(imageNamed: "bird_img_4.png")
var birdDeadTexture = SKTexture(imageNamed: "bird_img_dead.png")
/* ------------------------------------ Main Setup ------------------------------------------ */
override func didMoveToView(view: SKView) {
/* Setup your scene here */
println("Moved to Game Scene")
movingObjects.speed = 0
/* Background Image setup */
backgroundImage()
/* Set up deletates and physics and timer */
self.physicsWorld.contactDelegate = self
self.physicsWorld.gravity = CGVectorMake(0, -5)
self.addChild(movingObjects)
self.addChild(labelHolder)
/* Load Score Text */
scoreLabel.fontName = "Helvetica"
scoreLabel.fontSize = 60
scoreLabel.text = "0"
scoreLabel.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)+self.frame.size.height*0.3)
self.addChild(scoreLabel)
bird = SKSpriteNode(texture: birdTexture)
bird.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame))
// Make bird smaller
bird.size.height = bird.size.width/12
bird.size.width = bird.size.width/12
// Animate Bird
var animation = SKAction.animateWithTextures([birdTexture, birdTexture2, birdTexture3, birdTexture4], timePerFrame: 0.08)
var makeBirdFlap = SKAction.repeatActionForever(animation)
bird.runAction(makeBirdFlap)
// Load Physics
// birdPhysics()
// Run bird animation
bird.zPosition = 10
self.addChild(bird)
/* Introduce ground and top into the scene */
// Create Ground
var ground = SKSpriteNode()
ground.position = CGPointMake(CGRectGetMidX(self.frame), self.frame.size.height/100 * 16)
ground.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(self.frame.size.width, 1))
ground.physicsBody?.dynamic = false
ground.physicsBody?.categoryBitMask = objectGroup
// Add Ground to scene
self.addChild(ground)
// Create Top
var top = SKSpriteNode()
top.position = CGPointMake(0, self.frame.size.height)
top.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(self.frame.size.width, 1))
top.physicsBody?.dynamic = false
top.physicsBody?.categoryBitMask = objectGroup
// Add Top to scene
self.addChild(top)
}
/* ------------------------------------ Spawning Enemy Birds ------------------------------------------ */
/* Create and Spawn enemy birds */
func enemySpawn() {
let height = self.frame.size.height // screen height as variable
let width = self.frame.size.width // screen width as variable
var bottomBarHeight = self.frame.size.height*0.16 // bottom bar height
var spawningPoint = height - bottomBarHeight // screen height - 16%
var randSpawn = arc4random_uniform(UInt32(spawningPoint)) // random number between 0 and 645
var finalSpawn = CGFloat(randSpawn) + bottomBarHeight // add 16% (bottombarheight to the random number
/*
CHECK VALUES OF SPAWN
println("\(height) is the total screen height")
println("\(bottomBarHeight) is the pixels below the ground")
println("\(spawningPoint) is the random range")
println("\(randSpawn) is a random number")
println("\(finalSpawn) - Spawn Location")
println(enemyBird.position)
*/
if (enemyBird.position.y > 730) {
enemyBird.position.y = 720
}
if (enemyBird.position.y < 130) {
enemyBird.position.y = 135
}
// println(Int(enemyBird.position.y))
// Create enemy bird
var enemyBirdTexture = SKTexture(imageNamed: "enemy_img_2.png")
enemyBird = SKSpriteNode(texture: enemyBirdTexture)
enemyBird.position = CGPoint(x: CGRectGetMidX(self.frame)*2.5, y: finalSpawn)
enemyBird.size.height = enemyBird.size.height/12
enemyBird.size.width = enemyBird.size.width/12
enemyBird.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(enemyBird.size.width, enemyBird.size.height))
enemyBird.physicsBody?.dynamic = false
enemyBird.physicsBody?.categoryBitMask = objectGroup
// Move enemy birds
var moveEnemyBird = SKAction.moveByX(-self.frame.size.width * 2, y: 0, duration: NSTimeInterval(self.frame.size.width / 100)) //4.14 seconds on screen
var removeEnemyBird = SKAction.removeFromParent()
var moveAndRemoveEnemyBird = SKAction.sequence([moveEnemyBird, removeEnemyBird])
// Add enemy to scene and move enemy
enemyBird.runAction(moveEnemyBird)
movingObjects.addChild(enemyBird)
}
/* ------------------------------------ Other Parts ------------------------------------------ */
func backgroundImage() {
/* Put Background Image In */
// Create Background Texture
var bgTexture = SKTexture(imageNamed: "bg.png")
// Link bg variable to texture
bg = SKSpriteNode(texture: bgTexture)
// Position thr bg image
bg.position = CGPoint(x: CGRectGetMidX(self.frame), y: self.frame.height/2)
bg.size.height = self.frame.height
// Move background image left
var moveBg = SKAction.moveByX(-bgTexture.size().width, y: 0, duration: 9)
var replaceBg = SKAction.moveByX(bgTexture.size().width, y: 0, duration: 0)
var moveBgForever = SKAction.repeatActionForever(SKAction.sequence([moveBg, replaceBg]))
// Keep world never ending
for var i:CGFloat = 0; i < 3; i++ {
// Position Background
bg = SKSpriteNode(texture: bgTexture)
bg.position = CGPoint(x: bgTexture.size().width/2 + bgTexture.size().width * i, y: CGRectGetMidY(self.frame))
// Stretch background full height of screen
bg.size.height = self.frame.height
// Run the action to move BG
bg.runAction(moveBgForever)
self.addChild(bg)
}
}
func startTimers() {
/* Create Score Timer */
//scoreTimer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector:Selector("scoreCount"), userInfo: nil, repeats: true)
enemySpawnTimer = NSTimer.scheduledTimerWithTimeInterval(0.75, target: self, selector: Selector("enemySpawn"), userInfo: nil, repeats: true)
}
func birdPhysics() {
/* Give bird physics */
// Give bird physics
bird.physicsBody = SKPhysicsBody(circleOfRadius: bird.size.height/3)
bird.physicsBody?.mass = 0.2
bird.physicsBody?.dynamic = true
bird.physicsBody?.allowsRotation = false
bird.physicsBody?.categoryBitMask = birdGroup
bird.physicsBody?.collisionBitMask = objectGroup
bird.physicsBody?.contactTestBitMask = objectGroup
}
func didBeginContact(contact: SKPhysicsContact) {
if contact.bodyA.categoryBitMask == objectGroup || contact.bodyB.categoryBitMask == objectGroup {
scoreTimer.invalidate()
enemySpawnTimer.invalidate()
bird = SKSpriteNode(texture: birdDeadTexture)
if gameOver == 0 {
movingObjects.speed = 0
gameOver = 1
movingObjects.removeAllChildren()// Remove all enemies
gameOverLabel.fontName = "Helvetica"
gameOverLabel.fontSize = 25
gameOverLabel.text = "Tap to retry!"
gameOverLabel.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)*1.5)
labelHolder.addChild(gameOverLabel)
gameOverLabel.zPosition = 9
}
}
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
if (Menu == 0) {
movingObjects.speed = 1
birdPhysics()
startTimers()
}
if (gameOver == 0) { // Runs if game is not over
bird.physicsBody?.velocity = CGVectorMake(0, 0)
bird.physicsBody?.applyImpulse(CGVectorMake(0, 80))
Menu = 1 // Number on right is jump height
} else { // Runs if game is over
score = 0 // Score int is 0
scoreLabel.text = "0" // Score Label is 0
bird.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)) // Position Bird in center
bird.physicsBody?.velocity = CGVectorMake(0,0) // Cannot make bird jump
labelHolder.removeAllChildren() // Removes all labels
gameOver = 0 // Sets game over to 0 so game will run
movingObjects.speed = 1
startTimers()
}
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
}

Answer 1

You can just change the texture of the SKSpriteNode like,
sprite.texture = newTexture
Load the textures before the start of the game.
var birdAliveTexture = SKTexture(imageNamed: "bird_img_1.png")
var birdDeadTexture = SKTexture(imageNamed: "bird_img_dead.png")
var bird : SKSpriteNode!
When the sprite is loaded, give a name to the birdSprite.
bird = SKSpriteNode(texture: birdAliveTexture)
bird.name = "bird"
In didBeginContact function
func didBeginContact(contact: SKPhysicsContact) {
if contact.bodyA.categoryBitMask == objectGroup || contact.bodyB.categoryBitMask == objectGroup {
scoreTimer.invalidate()
enemySpawnTimer.invalidate()
bird.removeAllActions() //changed
bird.texture = birdDeadTexture // changed
if gameOver == 0 {
movingObjects.speed = 0
gameOver = 1
movingObjects.removeAllChildren()// Remove all enemies
gameOverLabel.fontName = "Helvetica"
gameOverLabel.fontSize = 25
gameOverLabel.text = "Tap to retry!"
gameOverLabel.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)*1.5)
labelHolder.addChild(gameOverLabel)
gameOverLabel.zPosition = 9
}
}
}