ios - swift 协议(protocol) : Adding Protocol conformance to an Instance

Question

我正在尝试了解如何在实例具有特定值的情况下向实例添加协议(protocol)一致性。这是我试图理解的“愚蠢”示例。

enum TypeOfFigure {
  case square, circle, triangle
}

protocol Figure {
    var type: TypeOfFigure { get }
}
protocol Square {}
protocol Circle {}
protocol Triangle {}


class FigureType: Figure {
    let type: TypeOfFigure

    init (type: TypeOfFigure) {
        self.type = type
        switch type {
        case .square: //extension self: Square {}
        case .circle: //extension self: Circle {}
        case .triangle: //extension self: Triangle {}
        }
    }

}

Answer 1

我建议另一种方法

你可以使用工厂方法:

class FigureTypeFactory {
    static func createFigure(withType type: TypeOfFigure) -> Figure {
        switch type {
            case .square: return new FigureSquare()
            case .circle: return new FigureCircle()
            case .triangle: return new FigureTriangle()
        }
    }
}

class Figure { }

class FigureSquare: Figure, Square { }