モグラたたきゲームで出現するモグラの数をランダムにしたい

Question

プログラミング初心者です。SpriteKitでゲームを作っております。
モグラたたきゲームでタイマーのメソッドを使用し3種類のモグラをランダムに出現させていますが、現在、全ての穴からモグラが一斉に出てくる状態になっています。この出現するモグラの数をランダムにしたいです。どなたかご教示いただきたく、よろしくお願いいたします。


```**該当のソースコード**

import UIKit
import SpriteKit
import GameplayKit
import AVFoundation

class GameScene: SKScene,SKPhysicsContactDelegate {

///モグラの位置
var enemyPoint = [[150,250],[250,600],[200,800],[500,400],[550,150],[650,700],[550,950],[300,1100]]

///モグラを入れる配列
var enemy01Array:[SKSpriteNode] = []
var enemy02Array:[SKSpriteNode] = []
var enemy03Array:[SKSpriteNode] = []

//タイマー
var enemyTimer = Timer()

override func didMove(to view: SKView) {

//もぐらの穴
for i in 0...7{
let hole = SKSpriteNode(imageNamed:"hole.png")
hole.position = CGPoint(x:enemyPoint[i][0],y:enemyPoint[i][1])
self.addChild(hole)
}

//タイマーの設定
enemyTimer = Timer.scheduledTimer(
timeInterval: 3.5,
target:self,
selector:#selector(GameScene.randomLoop),
userInfo:nil,repeats:true)
}

//モグラをランダムに表示
    @objc func randomLoop(){

for i in 0...7{
let random = Int(arc4random_uniform(20))

let enemy01 = SKSpriteNode(imageNamed: "enemy01.png")
enemy01.position = CGPoint(x:enemyPoint[i][0],y:enemyPoint[i][1])
enemy01.zPosition = 1

let enemy02 = SKSpriteNode(imageNamed: "enemy02.png")
enemy02.position = CGPoint(x:enemyPoint[i][0],y:enemyPoint[i][1])
enemy02.zPosition = 1


let enemy03 = SKSpriteNode(imageNamed: "enemy03.png")
enemy03.position = CGPoint(x:enemyPoint[i][0],y:enemyPoint[i][1])
enemy02.zPosition = 1


enemy01Array.append(enemy01)
enemy02Array.append(enemy02)
enemy03Array.append(enemy03)
    enemy01.name = "enemy01"
    enemy02.name = "enemy02"
    enemy03.name = "enemy03"


if(random>0 && random<13){
self.addChild(enemy01)

}else if(random>=13 && random<18){
self.addChild(enemy02)

}else{
self.addChild(enemy03)
}

let action1 = SKAction.wait(forDuration: 0.8,withRange:2.0)
let action2 = SKAction.hide()
let action3 = SKAction.wait(forDuration: 0.5,withRange:2.0)
let action4 = SKAction.unhide()
let actionS = SKAction.sequence([action1,action2,action3,action4])

enemy01.run(actionS)
enemy02.run(actionS)
enemy03.run(actionS)

    //Nodeが追加され続けてしまっていたタイマー追加までに消える
    DispatchQueue.main.asyncAfter(deadline: .now() + 3.0){
        let Node1 = self.childNode(withName: "enemy01")
        let Node2 = self.childNode(withName: "enemy02")
        let Node3 = self.childNode(withName: "enemy03")
        Node1?.removeFromParent()
        Node2?.removeFromParent()
        Node3?.removeFromParent()
    }
}
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch:AnyObject = touches.first{
let location = touch.location(in:self)
let touchNode = self.atPoint(location)

    if let name = touchNode.name {
        if name == "enemy01" {


let enemy01 = SKSpriteNode(imageNamed:"enemy01")
enemy01.position = touchNode.position
self.addChild(enemy01)

//モグラを1回転するアクション
let action1 = SKAction.rotate(byAngle: 6.28, duration: 0.2)
let action2 = SKAction.moveTo(y: touchNode.position.y + 150,duration: 0.2)
let actionG = SKAction.group([action1,action2])
let action3 = SKAction.removeFromParent()
let actionS = SKAction.sequence([actionG,action3])
enemy01.run(actionS)
touchNode.position.y = -100

}else if let name = touchNode.name {
    if name == "enemy02" {

let enemy02 = SKSpriteNode(imageNamed:"enemy02")
enemy02.position = touchNode.position
self.addChild(enemy02)

//モグラを1回転するアクション
let action1 = SKAction.rotate(byAngle: 6.28, duration: 0.3)
let action2 = SKAction.moveTo(y: touchNode.position.y + 150,duration: 0.3)
let actionG = SKAction.group([action1,action2])
let action3 = SKAction.removeFromParent()
let actionS = SKAction.sequence([actionG,action3])
enemy02.run(actionS)
touchNode.position.y = -100

}else if let name = touchNode.name {
    if name == "enemy03" {

let enemy03 = SKSpriteNode(imageNamed:"enemy03")
enemy03.xScale = 0.6
enemy03.yScale = 0.6
enemy03.position = touchNode.position
self.addChild(enemy03)

//モグラを1回転するアクション
let action1 = SKAction.rotate(byAngle: 6.28, duration: 0.3)
let action2 = SKAction.moveTo(y: touchNode.position.y + 150,duration: 0.3)
let actionG = SKAction.group([action1,action2])
let action3 = SKAction.removeFromParent()
let actionS = SKAction.sequence([actionG,action3])
enemy03.run(actionS)
touchNode.position.y = -100
}
}
}
    }
}
}

override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
}
}

```**使っているツールのバージョンなど補足情報**
swift3