Code from Object Oriented Swift project

protocols.swift

struct Point {
    let x: Int
    let y: Int

    func pointsAroundMe(withRange range: Int) -> [Point] {
        var results: [Point] = []

        for x in (self.x - range)...(self.x + range) {
            for y in (self.y - 1)...(self.y + 1) {
                let point = Point(x: x, y: y)
                results.append(point)
            }
        }

        return results
    }
}


class Enemy {
    var life: Int = 2
    let position: Point

    init(position: Point) {
        self.position = position
    }

    func decreaseHealth(factor: Int) {
        life -= factor
    }
}

class Tower {
    let position: Point
    var range: Int = 1
    var strength: Int = 1

    init(position: Point) {
        self.position = position
    }

    func fireAtEnemy(enemy: Enemy) {
        if inRange(self.position, range: self.range, target: enemy.position) {
            while enemy.life >= 0 {
                enemy.decreaseHealth(strength)
            }
            print("Enemy vanquished!")
        } else {
            print("Darn! Out of range!")
        }
    }

    func inRange(position: Point, range: Int, target: Point) -> Bool {
        let availablePositions = position.pointsAroundMe(withRange: range)
        for point in availablePositions {
            if point.x == target.x && point.y == target.y {
                return true
            }
        }
        return false
    }
}