Swift enum getting value of Int Enum using String value

Question

I have an enum thats raw value is Int. I know How to get the raw value. But I am accessing the data through webservice and there data for Enum is coming in String value.

Let me show you my Enum, then we will discuss the data that need to be convert into Enum and then getting the raw value.

My Enum:

enum ReportStatus : Int {
case None = 0
case Received = 2
case Forward = 9
case Reporting = 14
case Completed = 50
}

and the data I am getting from webservice is sending me value in string like so

var valueToCompareWithEnum = "Forward"

what I want:

I want to match that string value and to get the resultant int value. For example as I am receiving "Forward" So I must convert it in enum and getting the 9 Int value.

I know I can make switch case for it but I wanted to know if it can be handled with more clean way.....

Thanks in advance please help.

Joakim Danielson · Accepted Answer · 2019-09-04 14:13:02Z

3

You can let your enum implement CaseIterable and then compare your string to the string representation of each enum case using Array.first(where:)

enum ReportStatus : Int, CaseIterable {
    case None = 0
    case Received = 2
    case Forward = 9
    case Reporting = 14
    case Completed = 50

    static func translate(_ string: String) -> Int? {
        return ReportStatus.allCases.first(where: {string == "\($0)"})?.rawValue
    }
}

As a variant here is a global generic function that does the same but it returns the enum case rather than the raw value.

func translate<T: CaseIterable>(_ string: String, forEnum: T.Type) -> T? {
    return forEnum.allCases.first(where: {string == "\($0)"})
}

Usage

if let item = translate(valueToCompareWithEnum, forEnum: ReportStatus.self) {
    print(item.rawValue)
}

edited Sep 4, 2019 at 14:13

answered Sep 4, 2019 at 13:47

Joakim Danielson

53.1k5 gold badges36 silver badges79 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

200_OK · Accepted Answer · 2019-09-04 13:07:07Z

2

You can code like this;

enum ReportStatus : Int {
    case None = 0
    case Received = 2
    case Forward = 9
    case Reporting = 14
    case Completed = 50

    static func getRawValue(from value : String) -> Int {
        switch value {
        case "Forward":
            return self.Forward.rawValue
        case "Received":
            return self.Received.rawValue
        case "Reporting":
            return self.Reporting.rawValue
        case "Completed":
            return self.Completed.rawValue
        default:
            return self.None.rawValue
        }
    }

}


var valueToCompareWithEnum = "Forward"

let myVal = ReportStatus.getRawValue(from: valueToCompareWithEnum)

print(myVal) // 9

answered Sep 4, 2019 at 13:07

200_OK

9,5232 gold badges35 silver badges55 bronze badges

6 Comments

A.s.ALI Over a year ago

there is no clean method other than this?

200_OK Over a year ago

@A.s.ALI I guess .. YES.

trojanfoe Over a year ago

Apple always frowned on the use of the word "get" in methods. Has that changed with Swift or maybe it just applies to properties?

200_OK Over a year ago

@trojanfoe I always use get in my methods (both obj-c & swift) & I never faced any issue from the apple side. If you can give relevant link that will be more better to give you answer. I dont think Apple have any issue with this point.

trojanfoe Over a year ago

@dahiya_boy It's built into Objective-C, for example if you declare a property @property (readonly) Thing* thing; you can implement that by providing - (Thing*)thing { ... }. That won't work with - (Thing*)getThing { ... }. I don't know about Swift however.

|

Rob Napier · Accepted Answer · 2019-09-04 13:30:38Z

Since you're receiving these strings from a server, I assume you mean you're receiving them encoded in JSON. If so, then you likely want them to be Decodable. In that case, you can implement a custom decoder.

Before I show that, I'm going to rename your enum cases to match Swift style, which is a lowercase letter. I'm doing this to make the problem slightly harder and show more techniques you can use.

enum ReportStatus : Int {
    case none = 0
    case received = 2
    case forward = 9
    case reporting = 14
    case completed = 50
}

Here's the most straightforward approach:

extension ReportStatus: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        let stringValue = try container.decode(String.self)

        switch stringValue {
        case "None": self = .none
        case "Received": self = .received
        case "Forward": self = .forward
        case "Reporting": self = .reporting
        case "Completed": self = .completed
        default:
            throw DecodingError
                .valueNotFound(Self.self,
                               .init(codingPath: decoder.codingPath,
                                     debugDescription: "Unknown value for report status: \(stringValue)"))

        }
    }
}

This is a very good technique, but since our case names do match the server's keys closely (just not perfectly), we could fix that up by lowercasing the key:

enum ReportStatus : Int, CaseIterable { // Note CaseIterable
    case none = 0
    case received = 2
    case forward = 9
    case reporting = 14
    case completed = 50
}

extension ReportStatus: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        let stringValue = try container.decode(String.self)

        guard let value = Self.allCases.first(where: { String(describing: $0) == stringValue.lowercased() })
            else { throw DecodingError
                .valueNotFound(Self.self,
                               .init(codingPath: decoder.codingPath,
                                     debugDescription: "Unknown value for report status: \(stringValue)"))
        }
        self = value

    }
}

Ildar.Z · Accepted Answer · 2019-09-04 13:33:14Z

I recommend you switch Int enum to String to make it easer to parse and add one more field to get int value for each case:

enum ReportStatus: String {

    case none = "None"
    case received = "Received" 
    case forward = "Forward"
    case reporting = "Reporting"
    case completed = "Completed"

    var intValue: Int {
      switch self {
        case .none      : return 0 
        case .received  : return 2 
        case .forward   : return 9
        case .reporting : return 14
        case .completed : return 50
      }
   }
}


let valueToCompareWithEnum = "Forward"

if let myVal = ReportStatus(rawValue: valueToCompareWithEnum) {
    print(myVal.intValue) // 9
}

Because that data from web in String format it's kindly recommended parse it to String enum case and then use you'r own Int value where you need.

Collectives™ on Stack Overflow

Swift enum getting value of Int Enum using String value

4 Answers 4

Comments

6 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

6 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related