和大家一样,我也是Swift的新手。我不知道如何在enum中改变参数,在它创建之后。所以。有SimpleProtocol和SimpleEnum,它们符合这个协议。
//SimpleProto goes here
protocol ExampleProtocol {
var simpleDescription: String { get }
mutating func adjust()
}
//And SimpleEnum goes here
enum SimpleEnum : ExampleProtocol {
case first(Int)
case second(Int)
case third(Int)
var simpleDescription: String {
get {
var begining = "This is SimpleEnum with arg value : "
switch self {
case let .first(arg):
begining += "One"
case let .second(arg):
begining += "Two"
case let .third(arg):
begining += "Three"
}
return begining
}
}
mutating func adjust() {
//here i want to increase the value of enum's parameter on five
}
}
我确实能想出一个解决办法,但我觉得不够好。主要思想是用增加的值重新创建self:
case let .first(arg):
self = SimpleEnum.first(arg + 5)
任何想法?
不要将枚举视为可变类型。你会更快乐。在adjust
函数中,只返回一个新的enum值:
enum SimpleEnum {
...
func adjust() -> SimpleEnum {
switch self {
case let .first(arg):
return .first(arg + 5)
case let .second(arg):
return .second(arg + 5)
case let .third(arg):
return .third(arg + 5)
}
}
}