Swift Components and Entities

SwiftComponentsAndEntities.swift

//: Playground - noun: a place where people can play

import GameplayKit

class ShootingComponent: GKComponent {
    
    let power: Int
    
    init(power: Int) {
        self.power = power
    }
    
    func shooting(target: GKEntity) {
        let targetHealthComponent = target.componentForClass(HealtComponent)
        targetHealthComponent!.updateHealth(-power)
        print("new health is \(targetHealthComponent!.health)")
    }
}

class HealtComponent: GKComponent {
    
    var health: Int
    
    init(health: Int) {
        self.health = health
    }
    
    func updateHealth(health: Int) -> Void {
        self.health += health
    }
    
    override func updateWithDeltaTime(seconds: NSTimeInterval) {
        updateHealth(1)
        print("update health to \(health)")
    }
}

// creating componenets and entities
var enemyShootingComp = ShootingComponent(power: 10)
var myShootingComp = ShootingComponent(power: 20)

var enemyHealthComp = HealtComponent(health: 100)
var myHealthComp = HealtComponent(health: 100)

let enemy = GKEntity()
let mySelf = GKEntity()

enemy.addComponent(enemyShootingComp)
enemy.addComponent(enemyHealthComp)

mySelf.addComponent(myShootingComp)
mySelf.addComponent(myHealthComp)

// game system: health system created
// calling all health components
class HealthSystem: GKComponentSystem {
    
    // start all component's time dependent task
    override func updateWithDeltaTime(seconds: NSTimeInterval) {
        let clist = self.components
        for comp in clist {
            print("self healing called")
            comp.updateWithDeltaTime(seconds)
        }
        
    }
}

// just HealthComponent class will be accepted in the HealthSystem
let healthSystem = HealthSystem(componentClass: HealtComponent.self)
healthSystem.addComponentWithEntity(enemy)
healthSystem.addComponentWithEntity(mySelf)

print("---> time dependent task started")
// update all health components: enemy and my health
healthSystem.updateWithDeltaTime(10)

// starting actions: shootings
print("\n---> action/event dependent task started")
let attackerEnemyShootingComp = enemy.componentForClass(ShootingComponent)
attackerEnemyShootingComp?.shooting(mySelf)
let myAttackShootingComp = mySelf.componentForClass(ShootingComponent)
myAttackShootingComp?.shooting(enemy)

OUTPUT:
---> time dependent task started
self healing called
update health to 101
self healing called
update health to 101

---> action/event dependent task started
new health is 91
new health is 81

Nice, very simple to understand