如何使用按钮或滑块旋转精灵？

Question

I am making a game for iOS in Swift with SpriteKit, the game is currently just a ball moving around with a sword.

I have anchored the sword to the bottom of the sword, but I need to know how to control the direction of rotation with 2 buttons or a slider of some sort.

Here is my code:

import SpriteKit

let sprite = SKSpriteNode(imageNamed:"Player")
let weapon = SKSpriteNode(imageNamed: "weapon")

class GameScene: SKScene {
  override func didMoveToView(view: SKView) {
    let initialPlayerLocation = CGPoint(x: self.frame.width/2, y:       self.frame.height/2)
    /* Setup your scene here */

    //player
    sprite.setScale(1.0)
    sprite.position = initialPlayerLocation
    sprite.zPosition = 20
    self.addChild(sprite)

    //weapon
    weapon.setScale(1.0)
    weapon.position = initialPlayerLocation
    weapon.zPosition = -20
    weapon.anchorPoint = CGPointMake(0.5,0.0);

    self.addChild(weapon)


}

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    /* Called when a touch begins */

    for touch in (touches as! Set<UITouch>) {
        let location = touch.locationInNode(self)
        var move = SKAction.moveTo(location, duration:1.0)
        sprite.runAction(move)
        weapon.runAction(move)

    }
}

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
}
}

Answer 1

Okay, I think I understand what you are trying to do. It involves a lot of code, but in theory it is pretty simple. We detect if the touch is inside the left or right buttons (which in this example, I've made them SKSpriteNode s), and then set boolean values for the update method to use and rotate the weapon node (I'm assuming this is the sword you were talking about).

I've also included a variable that lets you set the speed of rotation. As you did not say what speed you were looking for, I left it up to you.

At the top of the program:

let sprite = SKSpriteNode(imageNamed:"Player")
let weapon = SKSpriteNode(imageNamed: "weapon")
let leftButton = SKSpriteNode(imageNamed: "leftButton")
let rightButton = SKSpriteNode(imageNamed: "rightButton")
var leftPressed = false
var rightPressed = false
let weaponRotateSpeed = 0.01 // Change this for rotation speed of weapon

And then modify touchesBegan to look like this:

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    /* Called when a touch begins */

    for touch in (touches as! Set<UITouch>) {
        let location = touch.locationInNode(self)
        if (leftButton.containsPoint(p: location))
            leftPressed = true
        else if (rightButton.containsPoint(p: location))
            rightPressed = true
        else {
            var move = SKAction.moveTo(location, duration:1.0)
            sprite.runAction(move)
            weapon.runAction(move)
        }
    }

In update , add this code:

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */

    if (leftPressed && rightPressed) {
        // Do nothing, as both buttons are pressed
    } else if (leftPressed) {
        weapon.zRotation -= weaponRotateSpeed
    } else if (rightPressed) {
        weapon.zRotation += weaponRotateSpeed
    }
}

We want to stop the weapon from rotating when we detect when the finger has moved off the button like so:

override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
    for touch in (touches as! Set<UITouch>) {
        let location = touch.locationInNode(self)
        if (leftButton.containsPoint(p: location))
            leftPressed = true
        else
            leftPressed = false

        if (rightButton.containsPoint(p: location))
            rightPressed = true
        else
            rightPressed = false
    }
}

And at last, we need to detect when your finger has left the screen:

override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)
        if (leftButton.containsPoint(p: location))
            leftPressed = false

        if (rightButton.containsPoint(p: location))
            rightPressed = false
    }
}