如何使用arc4random从数组中选择随机的SKShapeNode？ [英] How to choose a random SKShapeNode from an array using arc4random?

问题描述

我正在尝试使用Sprite Kit和Swift创建我的第一个应用程序。我创建了一个数组，并在其中填充了两个形状节点（如下所示。

I am trying to make my first app using sprite kit and swift. I have created an array and populated it with two shape nodes (shown below.

    //name the properties for enemy 1
    enemy1 = SKShapeNode (rectOfSize: CGSize(width: rectWidth/10, height: rectHeight/10))
    enemy1.position = first
    enemy1.fillColor = UIColor.blackColor()
    enemy1.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: rectWidth, height: rectHeight))
    enemy1.physicsBody?.dynamic = true
    enemy1.physicsBody?.affectedByGravity = false

    //name the properties for enemy 2
    enemy2 = SKShapeNode (rectOfSize: CGSize(width: rectWidth/10, height: rectHeight/10))
    enemy2.position = second
    enemy2.fillColor = UIColor.blackColor()
    enemy2.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: rectWidth, height: rectHeight))
    enemy2.physicsBody?.dynamic = true
    enemy2.physicsBody?.affectedByGravity = false



    //populate the arrays
    arrayOfEnemies1.addObject(enemy1)
    arrayOfEnemies1.addObject(enemy2)

假设我想每2秒将其中一个节点随机添加到场景中。我知道要使用arc4random，但是我不确定该怎么做。任何帮助将不胜感激。谢谢！

Say I wanted to add one of these nodes to a scene randomly, every 2 seconds. I know to use arc4random, but I am not sure how to do this. Any help would be greatly appreciated. Thanks!

推荐答案

您可以创建扩展名并获得如下所示的随机数组元素：

You can create an extension and get a random Array-element like that:

extension Array {
    func randomElement() -> T {
        let index = Int(arc4random_uniform(UInt32(self.count)))
        return self[index]
    }
}

就像这样：

var randomElement = arrayOfEnemies1.randomElement()

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