swift - 使用 Swift 创建随机 CGPoint

Question

所以，我正在尝试开发一个用 Swift 编写的简单游戏，但我在做一件非常简单的事情时遇到了麻烦。我无法设法创建随机 CGPoint...使用 arc4random 时，出现编译器错误，告诉我无法在 CGPoint 中使用 Int32。那么，有什么办法可以做到这一点？任何解决方法？谢谢!

Answer 1

也可以利用 Swift 对基类型的扩展来创建一组可重用的 CGPoint 重载函数。也许是这样的:

extension CGPoint {

    func random()->CGPoint { return CGPoint(x:Int(arc4random()%1000),y:Int(arc4random()%1000))}

    func random(range:Int)->CGPoint { 
         return CGPoint(x:Int(arc4random()%range),y:Int(arc4random()%range))}

    func random(rangeX:Int, rangeY:Int)->CGPoint { 
         return CGPoint(x:Int(arc4random()%rangeX),y:Int(arc4random()%rangeY))} 
}

然后您可以像这样编写随机 CGPoints:

var p = CGPoint.random() 
//random x and y with a range of 1000

或

var p = CGPoint.random(range:100)
//random x and y with a range of 100

或

var p = CGPoint.random(rangeX:200, rangeY:400)
//random x up to 200 and random y with a range of up to 400

当然，我现在不在 Xcode IDE 中检查语法/它是否编译正确但希望这能有所帮助 :-)

...

/////////////////

Swift 1.2 更新

/////////////////

似乎这些类型级别的函数调用不再允许扩展......至少对于 CGPoint 而言；可能是因为 CGPoint 实际上是一个结构，而不是基于当前 IOS 文档的类。

这是我的扩展的一个更深入的版本，它允许范围类型。

这已确认在 XCode 6.4 Beta 中有效

(带有 Playground 文件的 Github 存储库位于此处:

https://github.com/princetrunks/Random-CGPoint-Extension )

//creates random CGPoints in Swift as of XCode Beta 6.4 (6E7)
extension CGPoint {

/*private functions that help alleviate the ambiguity of the modulo bias 
   and nested typecasting as well as recycle similar functionality 
     for either Int or Range type parameter inputs */

private func randomInt(num:Int) ->Int{
    return Int(arc4random_uniform(UInt32(num)))
}

private func randomIntFromRange(numRange:Range<Int>) ->Int{
    return Int(arc4random_uniform(UInt32((numRange.endIndex - numRange.startIndex) + numRange.startIndex)))
}

//private variable for the default range
private var defaultRange : Int{
    get{return 1000}
}

//(a) public variable that creates a default random CGPoint
static var randomPoint = CGPoint.zeroPoint.random()


//(b) default random point creation
func random()->CGPoint { return CGPoint(x:randomInt(defaultRange),y:randomInt(defaultRange))}

//(c) using an Int parameter for both the random x and y range
func random(range:Int)->CGPoint {
    return CGPoint(x:randomInt(range),y:randomInt(range))
}

//(d) allows for the specification of the x and y random range
func random(#rangeX:Int, rangeY:Int)->CGPoint {
    return CGPoint(x:randomInt(rangeX),y:randomInt(rangeY))
}

//(e) allows the same functionality as (c) but with a Range<Int> type parameter
func random(range:Range<Int>)->CGPoint {
    return CGPoint(x:randomIntFromRange(range), y:randomIntFromRange(range))
}

//(f) allows the same functionality as (d) but with a Range<Int> type parameter
func random(#rangeX:Range<Int>, rangeY:Range<Int> )->CGPoint {
    return CGPoint(x:randomIntFromRange(rangeX), y:randomIntFromRange(rangeY))
 }

}

下面是我们如何测试这个扩展:

//(a)
let r  = CGPoint.randomPoint

//(b)
var anotherRandomPoint = r.random()

//(c)
anotherRandomPoint = r.random(1000)

//(d)
anotherRandomPoint = r.random(0...1000)

//(e)
anotherRandomPoint = r.random(rangeX:90, rangeY: 2000)

//(f)
anotherRandomPoint = r.random(rangeX:0...90, rangeY: 0...2000)


// generates 100 random CGPoints between -1000 and 999
for _ in 0...100 {
    anotherRandomPoint.random(-1000...1000)
}