所以我有一个接收 Any
的函数,它通过反射检查 Any 是否是一个枚举:
func extractRawValue(subject: Any) throws -> Any {
let mirror = Mirror(reflecting: subject)
guard let displayStyle = mirror.displayStyle,
case .`enum` = displayStyle else {
throw Errors.NoEnum
}
// And from here I don't know how to go any further...
// I wish I could do something like this:
guard let subject = subject as? RawRepresentable where let rawValue = subject.rawValue as Any else {
throw Errors.NoRawRepresenable
}
return rawValue
}
有谁知道我怎样才能完成这样的事情?
最佳答案
我认为执行此操作的 Swifty 方法是为您要使用的枚举使用协议(protocol):
protocol ValueAsAnyable {
func valueAsAny() -> Any
}
extension ValueAsAnyable where Self: RawRepresentable {
func valueAsAny() -> Any {
return rawValue as Any
}
}
func extractRawValue(subject: Any) throws -> Any {
let mirror = Mirror(reflecting: subject)
guard let displayStyle = mirror.displayStyle,
case .`enum` = displayStyle else {
throw Errors.NoEnum
}
guard let anyable = subject as? ValueAsAnyable else {
throw Errors.NoRawRepresentable
}
return anyable.valueAsAny()
}
let subject: Any = TestEnum.test
let thing = try? extractRawValue(subject: subject) //prints "test"
这应该允许你做你需要的,但保持类型安全。
关于swift - 我想将 RawRepresentable 的 rawValue 作为 Any 返回,但我只将它作为 Any 接收,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40535502/