Function enum parameter type

January 18, 2022

I am new on swift. I have 2+ enums and i would like to create enum to object generator function. I couldn’t find what type I should use for the Enum parameter in my function.

My enums;

public enum Animal: String, CaseIterable {
  case DOG = "dog"
  case CAT = "cat"
  case BIRD = "bird"
}

public enum Car: String, CaseIterable {
  case BMW = "bmw"
  case AUDI = "audi"
}

My Function;

  func enumToObj(Enum:TYPE?) -> Dictionary <String, String> {
    var enumsObject: [String:String] = [:];

    for enumData in Enum.allCases {
        let value = enumData.rawValue;
        enumsObject[value] = value;
    }

    return enumsObject;
  }

 //my expectation
 enumToObj(Animal) && enumToObj(Car)

>Solution :

You can define a generic function which take as argument a type that is CaseIterable and RawRepresentable:

func enumToObj<T>(_ Enum:T.Type) -> [String: T.RawValue]
    where T: CaseIterable & RawRepresentable
{
    var enumsObject: [String: T.RawValue] = [:];
    
    for enumData in Enum.allCases {
        let value = enumData.rawValue;
        enumsObject["\(enumData)"] = value;
    }
    
    return enumsObject;
}


print(enumToObj(Animal.self))
// ["CAT": "cat", "DOG": "dog", "BIRD": "bird"]

print(enumToObj(Car.self))
// ["AUDI": "audi", "BMW": "bmw"]

Using reduce(into:_:) this can also be written as

func enumToObj<T>(_ Enum:T.Type) -> [String: T.RawValue]
    where T: CaseIterable & RawRepresentable
{
    return Enum.allCases.reduce(into: [:]) { (enumsObject, enumData) in
        let value = enumData.rawValue;
        enumsObject["\(enumData)"] = value;
    }
}