ios - iOS 8.1 不再允许 CGPoint stringliteral

Question

在 iOS 8.0 中我有这个枚举:

enum Direction:CGPoint {
    case Top = "{0, -1}"
    case Right = "{1, 0}"
    case Down = "{0, 1}"
    case Left = "{-1, 0}"

    case TopLeft = "{-1, -1}"
    case TopRight = "{1, -1}"
    case DownLeft = "{-1, 1}"
    case DownRight = "{1, 1}"

    case None = "{0, 0}"
}

extension CGPoint: StringLiteralConvertible {

    public static func convertFromStringLiteral(value: StringLiteralType) -> CGPoint {
        return CGPointFromString(value)
    }

    public static func convertFromExtendedGraphemeClusterLiteral(value: StringLiteralType) -> CGPoint {
        return convertFromStringLiteral(value)
    }
}

现在这完全按照我想要的方式工作，我不得不使用字符串，因为简单的 case Top = CGPoint(x:0,y:1) 不起作用。

我像这样使用它，例如:

1. var Dir:Direction = .None
2. self.center.AddWithPoint(self.Dir.rawValue.multiply(CGFloat(Speed)))
3. bullet.Dir = .Right

这就是我在 8.1 之前使用枚举的方式，但现在不再允许了。

现在我遇到了很多这样的错误:

。类型“CGPoint”不符合协议(protocol)“StringLiteralConvertible”

。 “字符串”不能转换为“CGPoint”

那么有什么方法可以让它像以前一样工作吗？任何答案或建议都将不胜感激!

Answer 1

StringLiteralConvertible 协议(protocol)已更改，现在需要一个初始化器:

protocol StringLiteralConvertible : ExtendedGraphemeClusterLiteralConvertible {
    typealias StringLiteralType
    init(stringLiteral value: StringLiteralType)
}

另外，它继承自

protocol ExtendedGraphemeClusterLiteralConvertible : UnicodeScalarLiteralConvertible {
    typealias ExtendedGraphemeClusterLiteralType
    init(extendedGraphemeClusterLiteral value: ExtendedGraphemeClusterLiteralType)
}

又继承自

protocol UnicodeScalarLiteralConvertible {
    typealias UnicodeScalarLiteralType
    init(unicodeScalarLiteral value: UnicodeScalarLiteralType)
}

因此您可以将协议(protocol)实现为:

extension CGPoint: StringLiteralConvertible {

    public init(stringLiteral value: StringLiteralType) {
        self = CGPointFromString(value)
    }

    public init(extendedGraphemeClusterLiteral value: StringLiteralType) {
        self = CGPointFromString(value)
    }

    public init(unicodeScalarLiteral value: StringLiteralType) {
        self = CGPointFromString(value)
    }
}

示例用法:

 print(Direction.Top.rawValue)
 // Output: (0.0,-1.0)