一個小清新 Swift 游戲的開發全過程（Part 1）

class Circle {

    // MARK: Properties
    static var minRadius: Int {
        switch ScreenUtils.screenWidthModel() {
        case .Width320, .Width375, .Width414, .Other:
            return 20
        case .Width768:
            return 40
        case .Width1024:
            return 60
        }
    }
    static var maxRadius: Int {
        switch ScreenUtils.screenWidthModel() {
        case .Width320, .Width375, .Width414, .Other:
            return 50
        case .Width768:
            return 100
        case .Width1024:
            return 150
        }
    }
    var color: UIColor
    let radius: Int
    let center: CGPoint

    init(color:UIColor, radius:Int, center:CGPoint){
        self.color = color
        self.radius = radius
        self.center = center
    }

    class func randomCircle() -> Circle {
        let screenRect = UIScreen.mainScreen().bounds
        let screenWidth:CGFloat = screenRect.width
        let screenHeight:CGFloat = screenRect.height
        let randomRadius = minRadius + Int(arc4random_uniform(UInt32(maxRadius - minRadius + 1)))

        let areaWidth = Int(screenWidth) - (randomRadius << 1);
        let areaHeight = Int(screenHeight) - (randomRadius << 1) - 20;

        let x = randomRadius + Int(arc4random_uniform(100000)) % areaWidth
        let y = 20 + randomRadius + Int(arc4random_uniform(100000)) % areaHeight // below the status bar
        let randomPoint = CGPoint(x: x, y: y)

        let randomColor = ColorUtils.randomColor()
        let circle = Circle(color: randomColor, radius: randomRadius, center: randomPoint)
        return circle
    }

}

class CircleView: UIView {

    // MARK: Init
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    init(circle: Circle) {
        let frame = CGRectMake(0, 0, CGFloat(circle.radius*2), CGFloat(circle.radius*2))
        super.init(frame: frame)
        self.backgroundColor = circle.color
        self.center = circle.center
        self.layer.cornerRadius = CGFloat(circle.radius)
    }

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

</div>

#CircleFactory

CircleFactory 類是一個單例工廠類，維持一個 Circle 的數組，在每次游戲重新開始的時候會清空這個數組，并且通過 addCircle 向這個數組中添加新的 Circle 對象。添加新圓的邏輯很簡單，就是一個無限循環，直到算出來一個合格的圓為止。判斷圓是否可用的方法是 isCircleAvailable ，就是判斷兩個圓是否相交。但是屏幕區域畢竟是有限的，不可能會一直找到一個可用的圓，經過我的測試，圓的個數大于40的時候每次計算的耗時就會顯著增加，界面也會因為計算而卡住，好在這個游戲我還沒發現有那個超級大腦可以通過30回合（我朋友靠作弊才到26），所以游戲目前來說還不會遇到上述的極端情況。有個常量 MaxCircleCount 我設置成了40，期初的想法是游戲的終結就是第40回合，不過目前還沒有用到。代碼如下：

class CircleFactory: NSObject{

    // MARK: Properties
    static let MaxCircleCount = 40
    static let sharedCircleFactory = CircleFactory()
    let RadiusGap:Float = 10

    var circles = [Circle]()

    private override init() {
        self.circles.removeAll()
    }

    func addCircle() {
        while true {
            let aCircle = Circle.randomCircle()
            if isCircleAvailable(aCircle) {
                self.circles.append(aCircle)
                break
            }
            continue
        }
    }

    func isCircleAvailable(aCircle: Circle) -> Bool {
        for circle in self.circles {
            let distance = hypotf(
                Float(aCircle.center.x - circle.center.x),
                Float(aCircle.center.y - circle.center.y))
            let radiusLength = Float(aCircle.radius + circle.radius)
            if distance <= radiusLength + RadiusGap {
                return false
            }
        }
        return true
    }
}

override func viewDidLoad() {
       super.viewDidLoad()

       ...

       for circle in CircleFactory.sharedCircleFactory.circles {
           let color = ColorUtils.randomColor()
           circle.color = color
           let cv = CircleView(circle: circle)
           if circle === CircleFactory.sharedCircleFactory.circles.last! {
               self.lastCircleView = cv
           }
           self.view.addSubview(cv)
           circleViews.append(cv)

           ...
       }
 }

// MARK: Touch
    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {

        ...

        if touched {
            let touch = touches.first!
            let point = touch.locationInView(self.view)
            let sizeSide = CGFloat(CircleFactory.sharedCircleFactory.circles.last!.radius) + tolerance
            var roundedRect = lastCircleView.frame
            roundedRect.origin.x -= tolerance
            roundedRect.origin.y -= tolerance
            roundedRect.size.width += 2*tolerance
            roundedRect.size.height += 2*tolerance

            let maskPath = UIBezierPath(roundedRect: roundedRect,
                byRoundingCorners: UIRectCorner.AllCorners,
                cornerRadii: CGSizeMake(sizeSide, sizeSide))
            if maskPath.containsPoint(point) {
                // go to next round
            } else {
                // go to game over
            }
            touched = false
        }
}