CODEWITHSUNDEEP
iosswift
Arbitur
Arbitur

Reputation: 39091

Raw value for enum case must be a literal

I have this enum:

enum GestureDirection:UInt {
    case Up =       1 << 0
    case Down =     1 << 1
    case Left =     1 << 2
    case Right =    1 << 3
}

But on every case I get error:

Raw value for enum case must be a literal

I dont get it.

Swift 1.2, Xcode 6.3.2

Upvotes: 50

Views: 51741

Answers (4)

Martin R
Martin R

Reputation: 540005

(Answer updated for Swift 5 and later. Solutions for older Swift versions can be found in the edit history.)

For attributes which are not mutually exclusive you can use a struct and declare conformance to the OptionSet protocol. The advantage is that you get all bit operations for free.

You just have to define the underlying storage type and the pre-defined values:

struct GestureDirection : OptionSet {
    let rawValue : UInt8

    static let top   = Self(rawValue: 1 << 0)
    static let down  = Self(rawValue: 1 << 1)
    static let left  = Self(rawValue: 1 << 2)
    static let right = Self(rawValue: 1 << 3)
}

Usage:

// Initialize:
var direction : GestureDirection = [ .top, .right ]

// Test:
if direction.contains(.top) {
    // ...
}

// Add an option:
direction.insert(.left)

// Remove an option:
direction.remove(.right)

Upvotes: 21

ioopl
ioopl

Reputation: 1745

Swift 2.2 Version : In my case I needed to Convert the String Enum Values to be used in Localisable Strings. So added this method inside my enum.

    enum DisplayCellTitle: String {
    case Clear 

    func labelTitle() -> String {
        switch self {
        case .Clear:
            return "LBL_CLEAR".localizedWithComment("Clear")
        }
    }
}

And then Use it like so : 

        // Get the localised value of the Cell Label Title
    let lblTitle = DisplayCellTitle.labelTitle(cellTitle)()

where cellTitle passed in is just one of these CellTitle Enum Values

Upvotes: 11

Vincent Saluzzo
Vincent Saluzzo

Reputation: 1377

You seems to want a bitwise support for your enums, but if you regards a translation of NS_OPTIONS Objective-C in Swift, that's not represented by a Swift Enum but a struct inherit from RawOptionSetType.

If you need example or instructions, you can look at this NSHipster article

That's could be done with something like this : 

struct UIViewAutoresizing : RawOptionSetType {
    init(_ value: UInt)
    var value: UInt
    static var None: UIViewAutoresizing { get }
    static var FlexibleLeftMargin: UIViewAutoresizing { get }
    static var FlexibleWidth: UIViewAutoresizing { get }
    static var FlexibleRightMargin: UIViewAutoresizing { get }
    static var FlexibleTopMargin: UIViewAutoresizing { get }
    static var FlexibleHeight: UIViewAutoresizing { get }
    static var FlexibleBottomMargin: UIViewAutoresizing { get }
}

Regards,

Upvotes: 5

Benjamin Gruenbaum
Benjamin Gruenbaum

Reputation: 276506

That's because 1 << 0 isn't a literal. You can use a binary literal which is a literal and is allowed there:

enum GestureDirection:UInt {
    case Up =       0b000
    case Down =     0b001
    case Left =     0b010
    case Right =    0b100
}

Enums only support raw-value-literals which are either numeric-literal (numbers) string-literal­ (strings) or boolean-literal­ (bool) per the language grammar.

Instead as a workaround and still give a good indication of what you're doing.

Upvotes: 40

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