随机生成UIImageView

Question

想知道为什么这段代码会给我错误，＆＃34;无法指定类型的值＆＃39;（）＆＃39;输入＆＃39; CGPoint＆＃39;＆＃34;。当whiteDot覆盖smallDot时，我希望smallDot在屏幕上的随机位置产生。

class SecondViewController: UIViewController {

private var addOne = 0

func spawnRandomPosition() {

    let height = self.view!.frame.height
    let width = self.view!.frame.width

    let randomPosition = CGPoint(x:CGFloat(arc4random()).truncatingRemainder(dividingBy: height),
                                 y: CGFloat(arc4random()).truncatingRemainder(dividingBy: width))   

return smallDot.center = 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) {
        smallDot.image = nil;
        addOne += 1
        score.text = "\(addOne)"
    smallDot.center = spawnRandomPosition() //this is line giving error//
    }

    }


        }

Answer 1

它给出错误，因为spawnRandomPosition没有返回值。如果你修复它以返回你生成的坐标，你也可能需要将它分配给图像视图的坐标。

请参阅apple docs以了解返回函数的正确语法。 https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Functions.html

Answer 2

您没有从方法返回任何值。您需要返回CGPoint才能在handlePan:方法中使用它。定义函数返回值CGPoint并返回您计算的随机位置。

func spawnRandomPosition() -> CGPoint  {

    let height = self.view!.frame.height
    let width = self.view!.frame.width

    let randomPosition = CGPoint(x:CGFloat(arc4random()).truncatingRemainder(dividingBy: height),
                             y: CGFloat(arc4random()).truncatingRemainder(dividingBy: width))   

    return randomPosition 
}