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iOS Protocols in Swift Creating Flexible Objects Using Protocols Protocol Oriented Programming Part 2

Error: redeclaration

I keep on getting the error: invalid redeclaration of 'decreaseLife(by):'. I don't understand why, since it was originally declared within a protocol. Here is my code:

enum Direction { case up, down, left, right }

protocol Movable { func move(_ direction: Direction, by distance: Int) }

protocol Destructable { func decreaseLife(by factor: Int) }

protocol Player: Destructable { var position: Point { get set } var life: Int { get set } init(x:Int, y: Int) }

protocol Attacker { var strength: Int { get } var range: Int { get }

func attack(player: Player)

}

struct Point { let x: Int let y: Int

init(x: Int, y: Int) {
    self.x = x
    self.y = y
}

/// Returns the surrounding points in range of
/// the current one
func points(inRange range: Int = 1) -> [Point] {
    var results = [Point]()

    let lowerBoundOfXRange = x - range
    let upperBoundOfXRange = x + range

    let lowerBoundOfYRange = y - range
    let upperBoundOfYRange = y + range

    for xCoordinate in lowerBoundOfXRange...upperBoundOfXRange {
        for yCoordinate in lowerBoundOfYRange...upperBoundOfYRange {
            let coordinatePoint = Point(x: xCoordinate, y: yCoordinate)
            results.append(coordinatePoint)
        }
    }

    return results
}

}

// Enemy class Enemy: Player, Attacker { var life: Int = 2 var position: Point var strength: Int = 5 var range: Int = 2

required init(x: Int, y: Int) {
    self.position = Point(x: x, y: y)
}

func decreaseLife(by factor: Int) {
    life -= factor
}

//MARK: - Destructable
func decreaseLife(by factor: Int) {
    life -= factor
}

func attack(player: Player) {
    player.decreaseLife(by: strength)
}

func move(_ direction: Direction, by distance: Int) {
    switch direction {
        case .up: position = Point(x: position.x, y: position.y + 1)
        case .down: position = Point(x: position.x, y: position.y - 1)
        case .right: position = Point(x: position.x + 1, y: position.y)
        case .left: position = Point(x: position.x - 1, y: position.y)

    }
}

}

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

init(x: Int, y: Int) {
    self.position = Point(x: x, y: y)
}

func fire(at enemy: Enemy) {
    if isInRange(of: enemy) {
        enemy.decreaseLife(by: strength)
        print("Gotcha")
    } else {
        print("Darn! Out of range!")
    }
}

func isInRange(of enemy: Enemy) -> Bool {
    let availablePositions = position.points(inRange: range)

    for point in availablePositions {
        if point.x == enemy.position.x && point.y == enemy.position.y {
            return true
        }
    }

    return false
}

}

1 Answer

Chris Stromberg
PLUS
Chris Stromberg
Courses Plus Student 13,389 Points

You have declared this method twice with the same signature:

func decreaseLife(by factor: Int) {
    life -= factor
}

//MARK: - Destructable
func decreaseLife(by factor: Int) {
    life -= factor
}

You can't do that. Delete one, change the func name, or change the parameter name to fix the problem.

Otto linden
Otto linden
5,857 Points

To make Charlotte Dorn feel better he made the mistake in the video, but he corrected him self!