I'm currently making a game that will have multiple types of enemies, I currently made the basic enemy using a subclass of SKSpriteNode and everything is working fine. I now want to implement another sub class of the basic enemy since all the enemies are similar. I am having trouble creating the new subclass. Any help would be much appreciated. Here is my code...
class Basic_Fighter : SKSpriteNode {
var health : Int = 3
var ship_speed : Double = 7.0
var bullet_rapidness : Double = Double ((arc4random_uniform(3) + 2) )
var bullet_speed : Double = 3.0
var action = SKAction()
var bullet_Timer : NSTimer?
func subtract_health(){ health-- }
func enemy_killed(){
let action = SKAction.moveToY(-1000, duration: 5)
self.runAction(SKAction.repeatActionForever(action))
let rotateAction = SKAction.rotateByAngle(CGFloat(M_PI), duration: 3)
self.runAction(SKAction.repeatActionForever(rotateAction))
//Set a timer to destoy the node
_ = NSTimer.scheduledTimerWithTimeInterval(3.0, target: self, selector: Selector("destroy"), userInfo: nil, repeats: false)
}
func destroy(){
self.removeFromParent()
}
}
and the next enemy ....
class new_fighter : Basic_Fighter {
convenience init(){
self.init()
health = 5
}
}
I am not sure which exactly question are you asking, but this part is wrong:
class new_fighter : Basic_Fighter {
convenience init(){
self.init()
health = 5
}
}
You can not have convenience initializer declared just as is, without a designated initializer. Perhaps you should revisit Swift language reference for the part about designated vs. convenience initializers.
From the documentation:
... Swift applies the following three rules for delegation calls between initializers:
Rule 1
A designated initializer must call a designated initializer from its immediate superclass.
Rule 2
A convenience initializer must call another initializer from the same class.
Rule 3
A convenience initializer must ultimately call a designated initializer.
When you subclass SKSPriteNode you must use this designated initializer:
init(texture: SKTexture?, color: UIColor, size: CGSize)
and in your convenience initializer call: self.init(texture: texture, color: color, size: size)
Related
I'm trying to learn how to make a GameManager type class, and making individual classes for each of my GameScenes... probably the wrong thing to do, but for the sake of this question, please accept this as the way to do things.
My GameManager looks like this, having a reference to each of the scenes, that's static:
import SpriteKit
class GM {
static let scene2 = SecondScene()
static let scene3 = ThirdScene()
static let home = SKScene(fileNamed: "GameScene")
}
How do I create a SKScene programmatically, without size info, since they're in a subclass of SKScene and don't have any idea what the view size is, and I don't want them to need worry about this:
I'm doing this, but getting a EXC_BAD_Access at convenience override init()
class SecondScene: SKScene {
override init(size: CGSize){
super.init(size: size)
}
convenience override init(){
self.init()
self.backgroundColor = SKColor.red
self.anchorPoint = CGPoint(x: 0.5, y: 0.5)
}
}
As I mentioned your question is a bit vague but lets do some examples of what a GameManager class can be.
Before I start lets differentiate between calling this
let scene = StartScene(size: ...)
and this
let scene = SKScene(fileNamed: "StartScene")
The 1st method, with size, is when you create your scenes all in code and you are not using the xCode visual level editor.
The 2nd method is when you are using the Xcode level editor, so you would need to create a StartScene.sks file. Its that .sks file that it looks for in fileNamed.
Now for some game manager example, lets first imagine we have 3 SKScenes.
class StartScene: SKScene {
override func didMove(to view: SKView) { ... }
}
class GameScene: SKScene {
override func didMove(to view: SKView) { ... }
}
class GameOverScene: SKScene {
override func didMove(to view: SKView) { ... }
}
Lets say you want to transition from StartScene to GameScene, you would add this code in your StartScene at the correct spot e.g when the play button is pressed. Thats the simplest way to move from one SKScene to the next, directly from the SKScene itself.
// Code only, no xCode level editor
let gameScene = GameScene(size: CGSize(...))
let transition = SKTransition...
gameScene.scaleMode = .aspectFill
view?.presentScene(gameScene, transition: transition)
// With xCode level editor (returns an optional so needs if let
// This will need the GameScene.sks file with the correct custom class set up in the inspector
// Returns optional
if let gameScene = SKScene(fileNamed: "GameScene") {
let transition = SKTransition...
gameScene.scaleMode = .aspectFill
view?.presentScene(gameScene, transition: transition)
}
Now for some actual examples of GameManagers, Im sure you know about some of them already.
EXAMPLE 1
Lets say we want a scene loading manager. You approach with static methods will not work because a new instance of SKScene needs be created when you transition to one, otherwise stuff like enemies etc will not reset. Your approach with static methods means you would use the same instance every time and that is no good.
I personally use a protocol extension for this.
Create a new .swift file and call it SceneLoaderManager or something and add this code
enum SceneIdentifier: String {
case start = "StartScene"
case game = "GameScene"
case gameOver = "GameOverScene"
}
private let sceneSize = CGSize(width: ..., height: ...)
protocol SceneManager { }
extension SceneManager where Self: SKScene {
// No xCode level editor
func loadScene(withIdentifier identifier: SceneIdentifier) {
let scene: SKScene
switch identifier {
case .start:
scene = StartScene(size: sceneSize)
case .game:
scene = GameScene(size: sceneSize)
case .gameOver:
scene = GameOverScene(size: sceneSize)
}
let transition = SKTransition...\
scene.scaleMode = .aspectFill
view?.presentScene(scene, transition: transition)
}
// With xCode level editor
func loadScene(withIdentifier identifier: SceneIdentifier) {
guard let scene = SKScene(fileNamed: identifier.rawValue) else { return }
scene.scaleMode = .aspectFill
let transition = SKTransition...
view?.presentScene(scene, transition: transition)
}
}
Now in the 3 scenes conform to the protocol
class StartScene: SKScene, SceneManager { ... }
and call the load method like so, using 1 of the 3 enum cases as the scene identifier.
loadScene(withIdentifier: .game)
EXAMPLE 2
Lets make a game manager class for game data using the Singleton approach.
class GameData {
static let shared = GameData()
private init() { } // Private singleton init
var highscore = 0
func updateHighscore(forScore score: Int) {
guard score > highscore else { return }
highscore = score
save()
}
func save() {
// Some code to save the highscore property e.g UserDefaults or by archiving the whole GameData class
}
}
Now anywhere in your project you can say
GameData.shared.updateHighscore(forScore: SOMESCORE)
You tend to use Singleton for things where you only need 1 instance of the class. A good usage example for Singleton classes would be things such as helper classes for Game Center, InAppPurchases, GameData etc
EXAMPLE 3
Generic helper for storing some values you might need across all scenes. This uses static method approach similar to what you were trying to do. I like to use this for things such as game settings, to have them in a nice centralised spot.
class GameHelper {
static let enemySpawnTime: TimeInterval = 5
static let enemyBossHealth = 5
static let playerSpeed = ...
}
Use them like so in your scenes
... = GameHelper.playerSpeed
EXAMPLE 4
A class to manage SKSpriteNodes e.g enemies
class Enemy: SKSpriteNode {
var health = 5
init(imageNamed: String) {
let texture = SKTexture(imageNamed: imageNamed)
super.init(texture: texture, color: SKColor.clear, size: texture.size())
}
func reduceHealth(by amount: Int) {
health -= amount
}
}
Than in your scene you can create enemies using this helper class and call the methods and properties on it. This way you can add 10 enemies easily and individually manage their health etc. e.g
let enemy1 = Enemy(imageNamed: "Enemy1")
let enemy2 = Enemy(imageNamed: "Enemy2")
enemy1.reduceHealth(by: 3)
enemy2.reduceHealth(by: 1)
Its a massive answer but I hope this helps.
This question already has answers here:
Creating a subclass of SKShapeNode
(1 answer)
Adding Convenience Initializers in Swift Subclass
(4 answers)
Closed 5 years ago.
Why it's possible to instantiate a SKShapeNode like this
let circle = SKShapeNode(circleOfRadius: 10)
But when i want to create a class that inherit form SKShapeNode i cant do something like this:
public class Player:SKShapeNode{
public var playerName : String
private var inventory: [enumObject]
init(nameOfPlayer:String, position:CGPoint, radious: CGFloat) {
super.init(circleOfRadius: radious)
self.position = position
self.fillColor = SKColor.white
playerName = nameOfPlayer
inventory = [enumObject]()
}
}
It says that this init is not the designed init for SKShapeNode, I searched about it but couldn't find the right way of creating this damn circle.
SKShapeNode.init(circleOfRadius:) is a convenience initializer on SKShapeNode so you can't call it from a Swift initializer. Swift enforces the designated initializer pattern more strictly than Objective C does.
Unfortunately, it appears the designated initializer for SKShapeNode is just init, so you'll need to do something like this:
public class Player: SKShapeNode {
public var playerName : String
private var inventory: [enumObject]
init(nameOfPlayer:String, position:CGPoint, radius: CGFloat) {
playerName = nameOfPlayer
inventory = [enumObject]()
super.init()
self.path = CGPath(ellipseIn: CGRect(origin: .zero, size: CGSize(width: radius, height: radius)), transform: nil)
self.position = position
self.fillColor = SKColor.white
}
// init?(coder:) is the other designated initializer that we have to support
public required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
The code above works for subclassing SKShapeNode, but given the API that Apple provides and considering how your code might need to change in the future, it might make more sense to create an SKNode subclass that contains one or more SKShapeNodes. In this setup, if you wanted to represent the player as more than just a simple circle, you could simply add additional nodes to the player node.
I want to create a SKShapeNode at a higher level than the touchesBegan of a SpriteNode so when I want to add the SKShapeNode to the screen from the touchesBegun event on this sprite, the shape already exists, and I simply add it to the screen from within the touchesBegan override.
TL;DR, in my SKSpriteNode, I'm trying to pre-build the SKShapeNode that will be used as an animated ring when the Sprite is touched.
I'd like to create the SKShapeNode with variable/constants, so I can easily edit its values...
So in the root of the subclass I have variables for color, size, and linewidth, ready to be used in the creation of the SKShapeNode...
class Balls: SKSpriteNode {
var ringSize: CGFloat = 64
var ringColor: SKColor = SKColor.white
var ringWidth: CGFloat = 16
....
Further down, but still at the root of the class, I create my ring:
let ring = SKShapeNode(circleOfRadius: ringSize)
And am instantly greeted with the lovingly cryptic:
Can not use instance member 'ringSize' within property initializer,
property initializers run before 'self' is available.
Fine. Ok. I get it. You want to think that a functional call to a class to create a property should be done before values are assigned to self. Neither here nor there, I think I'm getting cunning and can get around that by wrapping everything in a function:
class Balls: SKSpriteNode {
var ringSize: CGFloat = 64
var ringColor: SKColor = SKColor.white
var ringWidth: CGFloat = 16
var myRing = SKShapeNode()
func createRing() -> SKShapeNode{
let ring = SKShapeNode(circleOfRadius: ringSize)
ring.strokeColor = ringColor
ring.lineWidth = ringWidth
return ring
}
This generates no errors, and my excitement builds.
So I add another line, to create the actual ring:
....
myRing = createRing()
Dead again:
! Expected
declaration
I have absolutely no idea what this means and began to randomly attempt weird things.
One of them is heading into my already messy convenience initializer and adding myRing = createRing() in there... and this WORKS!
How and why does this work, and is this the best/right/proper way to be circling the drain of initialization?
:: EDIT:: UPDATE :: Full Code Context ::
Here's the full class with my bizarre and misunderstood initialisers.
import SpriteKit
class Circle: SKSpriteNode {
var ringSize: CGFloat = 96
var ringColor: SKColor = SKColor.white
var ringWidth: CGFloat = 8
var myRing = SKShapeNode()
override init(texture: SKTexture?, color: UIColor, size: CGSize) {
super.init(texture: texture, color: color, size: size)
}
convenience init() {
self.init(color: SKColor.clear, size: CGSize(width: 100, height: 100))
myRing = createRing()
addChild(myRing)
print("I'm on the screen")
explodeGroup = create_explosionActionGroup()
}
convenience init(color: UIColor, size: CGSize, position: CGPoint) {
self.init(color: color, size: size)
self.position = position
myRing = createRing()
explodeGroup = create_explosionActionGroup()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func createRing() -> SKShapeNode{
let ring = SKShapeNode(circleOfRadius: ringSize)
ring.strokeColor = ringColor
ring.lineWidth = ringWidth
return ring
}
Your createRing() method is inside Ball class so you need to create an instance of Ball first.
Simple way - You can change creation of instance to
let ball = Balls()
let myRing = ball.createRing()
I'm slightly confused as to where you placed the
myRing = createRing()
line of code but I'm wondering if this setup would help solve your problem
lazy var myRing: SKShapeNode = {
let ring = SKShapeNode(circleOfRadius: ringSize)
ring.strokeColor = ringColor
ring.lineWidth = ringWidth
return ring
}()
This way myRing would be created when it was accessed which should be after the Balls class is instantiated which would mean that ringSize, ringColor and ringWidth would all exist.
Based on your update I think your best bet might be to just make your three ring variables ‘static let’ instead. That way they will exist and have the set value before initializing the main class. The errors you’re seeing are because you created instance variables. Those will only exist when the instance has been initialized. So if you tried to call the ring method as the declaration of the variable or if you did it within the init before self/super init is called then the instance variables wouldn’t be accessible. The most recent code you’ve added should be working because you create the instance before attempting to generate the ring. I hope that makes sense and helps.
And am instantly greeted with the lovingly cryptic:
Can not use instance member 'ringSize' within property initializer, property initializers run before 'self' is available.
So one way around this problem would be to make the default ringSize available another way, e.g.
static let defaultRingSize: CGFloat = 64
var ringSize: CGFloat = Circle.defaultRingSize
let ring = SKShapeNode(circleOfRadius: Circle.defaultRingSize)
... but I question why you even have a var ringSize property like that. Shouldn't you have a didSet observer on it, so that if you change its value, you can update the shape of ring?
Dead again:
! Expected declaration
You weren't clear, in your question, how you actually triggered this, but I guess you tried something like this:
class Circle: SKSpriteNode {
var ringSize: CGFloat = 96
var myRing = SKShapeNode()
myRing = createRing() // “Expected declaration” error on this line
The problem here is that you've placed a statement in the body of your class, but only declarations are allowed in the body.
One of them is heading into my already messy convenience initializer and adding myRing = createRing() in there... and this WORKS!
How and why does this work
All of your class's own instance variables must be initialized before a super.init call. Since myRing has a default value, the compiler effectively inserts the initialization of myRing before the call to super.init in your designated initializer, like this:
override init(texture: SKTexture?, color: UIColor, size: CGSize) {
// Compiler-inserted initialization of myRing to the default
// value you specified:
myRing = SKShapeNode()
super.init(texture: texture, color: color, size: size)
}
Since you declared var myRing, you can then change it later to the customized SKShapeNode you really want.
is this the best/right/proper way to be circling the drain of initialization?
Well, “circling the drain” means “failing”, so I guess you're asking if this is “the best/right/proper way” to fail at initialization… I suppose it's not the best way to fail, since you didn't actually fail in the end.
Or maybe you meant “I hate the way Swift does initialization so I'm going to throw some shade”, in which case, you ain't seen nothin' yet.
But maybe you really meant “is this the best/right/proper way to initialize my instance”, in which case, well, “best” and “right” and “proper” are pretty subjective.
But I can objectively point out that you're creating an SKShapeNode (as the default value of myRing) just to immediately throw it away and create another SKShapeNode. So that's a waste. You've also got calls to createRing in both of your convenience initializers, but you could factor them out into the designated initializer.
But I wouldn't even do it quite like that. SKShapeNode's path property is settable, so you can just create a default SKShapeNode and then change its path after the call to super.init. That also makes it easier to handle changes to ringSize and the other properties, because you can funnel all the changes through a single method that knows how to make myRing match the properties.
Here's how I'd probably write your class:
import SpriteKit
class Circle: SKSpriteNode {
var ringSize: CGFloat = 96 {
// Use an observer to update myRing if this changes.
didSet { configureMyRing() }
}
var ringColor = SKColor.white {
didSet { configureMyRing() }
}
var ringWidth: CGFloat = 8 {
didSet { configureMyRing() }
}
// This can be a let instead of a var because I'm never going to
// set it to a different object. Note that I'm not bothering to
// initialize myRing's path or any other property here, because
// I can just call configureMyRing in my init (after the call to
// super.init).
let myRing = SKShapeNode()
override init(texture: SKTexture?, color: SKColor, size: CGSize) {
super.init(texture: texture, color: color, size: size)
// Call this now to set up myRing's path and other properties.
configureMyRing()
}
convenience init() {
self.init(color: SKColor.clear, size: CGSize(width: 100, height: 100))
// No need to do anything to myRing now, because my designated
// initializer set it up completely.
addChild(myRing)
print("I'm on the screen")
// Commented out because you didn't provide this property
// or method in your question.
// explodeGroup = create_explosionActionGroup()
}
convenience init(color: SKColor, size: CGSize, position: CGPoint) {
self.init(color: color, size: size)
self.position = position
// Commented out because you didn't provide this property
// or method in your question.
// explodeGroup = create_explosionActionGroup()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func configureMyRing() {
myRing.path = CGPath(ellipseIn: CGRect(x: -ringSize / 2, y: -ringSize / 2, width: ringSize, height: ringSize), transform: nil)
myRing.strokeColor = ringColor
myRing.lineWidth = ringWidth
}
}
I want to be able to make two variables available to the entire SKScene, and all functions inside of it. One of these variable using the other one to create its value. I understand why I cannot do this, but I don't know a fix for it. I have this code:
class GameScene: SKScene {
let num : CGFloat = 1.25
let reciprocal = 1 / num // <— This Line
override func sceneDidLoad() {
}
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
}
}
But I am obviously getting an error the line 4.
Cannot use instance member 'num' within property initializer; property
initializers run before 'self' is available
This means that I cannot use the variable because it is connected to the skscene, and the scene hasn't been implemented fully yet. Is there a way to declare this variable without throwing an error and making it assessable everywhere within this class?
Since reciprocal depends directly upon num, it could make sense to let the prior be a computed property based on the latter
class GameScene: SKScene {
let num: CGFloat = 1.5
var reciprocal: CGFloat { return 1/self.num }
// ...
}
Since num is an immutable property and will never change at runtime, another alternative is to let reciprocal be a lazy variable, computed upon its first use
class GameScene: SKScene {
let num: CGFloat = 1.5
lazy var reciprocal: CGFloat = { return 1/self.num }()
// ...
}
(Or, implement your own custom initializer for the GameScene, where you can initialize num and reciprocal to e.g. a given value and its reciprocal, respectively).
I'm trying to write two Swift classes, one is a subclass of the other and needs to take one of the superclass' properties and use that to configure its self.
class BaseClass {
let someValue: Double
let size: CGSize
init (size: CGSize) {
self.size = size
self.someValue = size.width / 2.0 //Doesn't really matter how this is calculated
}
}
class Subclass: BaseClass {
let someNewValue: Double
override init(size: CGSize) {
super.init(size: size)
self.someNewValue = self.someValue * 2
}
}
The problem is that the subclass requires that its call to super.init is after it sets initial values for all of its properties. However the self.someNewValue = self.someValue * 2 call which does this, relies on the super's init having been called first to set self.someValue. I guess I could get around this by turning let someValue: Double to var someValue: Double on the BaseClass, and then set its value in the subclass's init as well as the base class's init, but that just seems bad.
I see two solutions here:
Make someNewValue implicitly unwrapped optional
class Subclass: BaseClass {
let someNewValue: Double!
override init(size: CGSize) {
super.init(size: size)
self.someNewValue = self.someValue * 2
}
}
or give someNewValue some default value before calculating its final value
class Subclass: BaseClass {
let someNewValue: Double = 0.0
override init(size: CGSize) {
super.init(size: size)
self.someNewValue = self.someValue * 2
}
}
Both approches shouldn't cause any problems