A Switch With A String Enum Is Not Being Recoginized

Question

I have a CIFilter I want to do some effects to. I have an enum of type String

enum FilterType:String{
        case Sepiatone = "CISepiatone"
        case FalseColor = "CIFalseColor"
    }

But if I try the below code, the enum is NOT being treated as a string

 private class func createFilter(inout filter:CIFilter!,filterName:FilterType)
    {
        switch filterName{
        case .Sepiatone:
            filter = CIFilter(name: filterName) //ERROR "Extra argument 'name' in call
        default:
            println("Filter name is not a match")
        }
    }

The error message means its not seeing my enum type as a string and as such thinks I'm using the wrong init.

Do you know what is wrong with my switch statement?

Antonio · Accepted Answer · 2014-10-15 17:22:06Z

2

You have to use the rawValue property to obtain the raw value from an enum:

filter = CIFilter(name: filterName.rawValue)

Just for completeness, similarly you can use an initializer to obtain an enum case from a raw value:

var filterType = FilterType(rawValue: "CISepiatone")

Addendum: I think you are using an unnecessary switch in your filterName() method. If the FilterType enum contains valid filters only, a variable of FilterType type cannot contain a value that is not one of them. So in my opinion this implementation should work:

private class func createFilter(inout filter:CIFilter!,filterName:FilterType)
{
    filter = CIFilter(name: filterName.rawValue)
}

Moreover, using a parameter as a return value is not recommended, unless you have a good reason for that - you can just let the function return the filter:

func createFilter(filterName:FilterType) -> CIFilter
{
    return CIFilter(name: filterName.rawValue)
}

Last, you can just get rid of that function and add a CIImage extension:

extension CIFilter {
    convenience init (filterType: FilterType) {
        self.init(name: filterType.rawValue)
    }
}

let filterType = FilterType.FalseColor
let filter = CIFilter(filterType: filterType)

Isn't it just simpler?

NOTE: if you are, like me, are using Xcode 6.0.x, replace filterName.rawValue with filterName.toRaw() and FilterType(rawValue: filterName) with FilterType.fromRaw(filterName).

edited Oct 15, 2014 at 17:22

answered Oct 15, 2014 at 16:45

Antonio

72.8k11 gold badges152 silver badges170 bronze badges

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

5 Comments

Martin R Over a year ago

Side note: In Xcode 6.1, toRaw() and fromRaw() have been replaced by a property and a constructor, see stackoverflow.com/questions/25919075/….

Antonio Over a year ago

I'm still using 6.0.1 - but thanks for that, I'm updating my answer accordingly

Aggressor Over a year ago

Great answer thank you. Regarding the return type, yes I normally do that. However I have created a set of classes called 'processors', and their job it take an object and mutate it. So to me it seems logical that I pass it an image, and the processor mutates it. Or would you suggest otherwise?

Antonio Over a year ago

No, I don't have any suggestion, without a proper understanding of what your processors do. But that looks like a good reason for having a method with that signature.

Aggressor Over a year ago

I love how helpful the Stack community is! Make every answer count, I love it!

Collectives™ on Stack Overflow

A Switch With A String Enum Is Not Being Recoginized

1 Answer 1

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related