Creazione di un percorso semicerchio con CGPath e seguire il percorso con SKAction

Question

Non ho idea di come creare un percorso semicerchio con CGPath. V'è il codice che ho:

let path = CGPathCreateMutable() 
    let Width: CGFloat = 38.0 
    let radius: CGFloat = (Width/2.0) + (Treshold/2.0) 
    CGPathAddArc(pathOne, nil, x, 0.0, radius, firstPoint.position.x, secondPoint.position.x, true) 
    let waitAction = SKAction.waitForDuration(1.0) 
    let moveAction = SKAction.followPath(pathOne, duration: 3.0) 
    capOne.runAction(SKAction.sequence([waitAction, moveAction])) 

Answer 1

import SpriteKit 

class GameScene: SKScene, SKPhysicsContactDelegate { 

    override init(size: CGSize) { 
     super.init(size: size) 
     let square = SKSpriteNode(color: SKColor.redColor(), size: CGSizeMake(20, 20)) 
     square.position = CGPointMake(self.size.width/2, self.size.height/2) 
     addChild(square) 

     let bezierPath = UIBezierPath(arcCenter: CGPointMake(0, 0), radius: 100, startAngle: CGFloat(M_PI_2), endAngle: CGFloat(-M_PI_2), clockwise: false) 

     let pathNode = SKShapeNode(path: bezierPath.CGPath) 
     pathNode.strokeColor = SKColor.blueColor() 
     pathNode.lineWidth = 3 
     pathNode.position = square.position 
     addChild(pathNode) 

     square.runAction(SKAction.followPath(bezierPath.CGPath, asOffset: true, orientToPath: true, duration: 2)) 
    } 

    required init?(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 
}