特定图像生成

Question

如何编辑此代码以使 spawnRandomPosition 函数也不允许图像从屏幕底部向下生成 45 像素？所以屏幕顶部的 45 个像素无法生成。

class SecondViewController: UIViewController {

private var addOne = 0

func spawnRandomPosition() -> CGPoint
{                
    let width  = UIScreen.main.fixedCoordinateSpace.bounds.width
    let height = UIScreen.main.fixedCoordinateSpace.bounds.height

    let centerArea = CGRect(x: UIScreen.main.fixedCoordinateSpace.bounds.midX - 75.0 / 2,
                            y: UIScreen.main.fixedCoordinateSpace.bounds.midY - 75.0 / 2,
                            width: 75.0,
                            height: 75.0)

    while true
    {
        let randomPosition = CGPoint(x: Int(arc4random_uniform(UInt32(width))), y: Int(arc4random_uniform(UInt32(height))))


        if !centerArea.contains(randomPosition)
        {
            return randomPosition
        }
    }
}

@IBAction func handlePan(recognizer:UIPanGestureRecognizer) {
let translation = recognizer.translation(in: self.view)
if let view = recognizer.view {
    view.center = CGPoint(x:view.center.x + translation.x,
                          y:view.center.y + translation.y)
     }
recognizer.setTranslation(CGPoint.zero, in: self.view)

if (WhiteDot.frame.contains(smallDot.frame) && smallDot.image != nil) {
    addOne += 1
    score.text = "\(addOne)"
    smallDot?.center = spawnRandomPosition()

}
}
    }

Answer 1

也许你需要一种不同的方法，虽然不优雅，但你可以使用 if's

func spawnRandomPosition() -> CGPoint  {

let screenWidth  = UIScreen.main.fixedCoordinateSpace.bounds.width
let screenHeight = UIScreen.main.fixedCoordinateSpace.bounds.height
boolean valid = true;
repeat
{
   let randomPosition = CGPoint(x:CGFloat(arc4random()),y:arc4random())
   if(randomPosition.x >screenWidth || randomPosition.y < 45 || (randomPosition.x > ((screenWidth/2)- 37.5) && randomPosition.x< ((screenWidth/2)+ 37.5)  || (randomPosition.y > ((screenHeight/2)- 37.5) && randomPosition.y< ((screenHeight/2)+ 37.5))
      valid = false
}while(valid = false;)
}

当然你应该考虑到 arc4random() 可能会返回一个非常高的数字并最终得到一个低效的解决方案，所以你可以使用 rand() 代替

Answer 2

稍微修改一下函数spawnRandomPosition：

func spawnRandomPosition() -> CGPoint
{
    let minY: CGFloat = 45.0

    let width  = UIScreen.main.fixedCoordinateSpace.bounds.width
    let height = UIScreen.main.fixedCoordinateSpace.bounds.height - minY

    let centerArea = CGRect(x: UIScreen.main.fixedCoordinateSpace.bounds.midX - 75.0 / 2,
                            y: UIScreen.main.fixedCoordinateSpace.bounds.midY - 75.0 / 2,
                            width: 75.0,
                            height: 75.0)

    while true
    {
        let randomPosition = CGPoint(x:CGFloat(arc4random()).truncatingRemainder(dividingBy: height),
                                     y:minY + CGFloat(arc4random()).truncatingRemainder(dividingBy: width))

        // Check for 'forbidden' area
        if !centerArea.contains(randomPosition)
        {
            return randomPosition
        }
    }
}