Question

enum DocumentType : String
{
    case
    Any = "Any",
    DL = "DL",
    Passport = "Passport",
    Invalid
}

我正在使用像这样的rawValue构造函数

if let d = DocumentType(rawValue: type) {

解析来自服务器的任何内容。

现在，假设服务器端的昏暗灯泡将DL更改为D1服务器端 - ＆gt; 解析器将默认值中断为无效。

是否有windows-developer证明解析器的规定没有手动写一个长的if else雏菊？同样的问题与白痴在json中改变键的情况。需要一些方法来以一种不那么好的开发人员的方式读出json。感谢。

Answer 1

我不认为你可以忽略大小写，但是如果没有if / else语句链，你可以创建一个初始化来防止你的特定问题：

enum DocumentType : String
{
    case
    Any = "Any",
    DL = "DL",
    Passport = "Passport",
    Invalid
    init?(raw:String) {
        let str = raw.characters.count > 2 ?  raw.capitalizedString : raw.uppercaseString
        if let d = DocumentType(rawValue: str) {
            self = d
        }
        else {
            return nil
        }
    }

}

if let d = DocumentType(raw: "ANY") {
    print("success!")
}

Answer 2

适用于所有相关枚举的通用扩展。枚举必须遵守 String 和 CaseIterable 协议才能使其正常工作。

import Foundation
extension CaseIterable where Self:RawRepresentable, RawValue == String  {
    init?(rawValueIgnoreCase: RawValue) {
        if let caseFound = Self.allCases.first(where: { $0.rawValue.caseInsensitiveCompare(rawValueIgnoreCase) == .orderedSame }) {
            self = caseFound
        } else {
            self.init(rawValue: rawValueIgnoreCase)
        }
    }
}

enum FooBar: String, CaseIterable {
    case foo
    case bar = "BAR"
}

let foo = FooBar(rawValueIgnoreCase: "foo")
let FOO = FooBar(rawValueIgnoreCase: "FOO")
let FoO = FooBar(rawValueIgnoreCase: "FoO")
let bar = FooBar(rawValueIgnoreCase: "bar")
let Bar = FooBar(rawValueIgnoreCase: "Bar")
let BAR = FooBar(rawValueIgnoreCase: "BAR")
let oops = FooBar(rawValueIgnoreCase: "oops") // nil

Answer 3

我们可以通过在初始化枚举时更改案例来实现此目的。

 enum DocumentType : String {
    case any = "ANY"
    case dl = "DL"
    case passport = "PASSPORT"
    case invalid = "INVALID"

    //If you want to display status in UI define your display name
    var documentDisplayType: String {
     switch self  {
       case .any:
            return "Any"
       case .dl:
            return "Driving License"
       case .passport:
            return "Passport"
       case invalid:
            return "Not proper document"
    }
}

虽然initaliziing使用uppercased()函数将respose文档类型更改为大写。

 let type = "Dl"
 let docType = DocumentType(rawValue: type.uppercased())
 print(docType.documentDisplayType) // Prints DL

枚举rawValue构造函数忽略大小写

3 个答案: