ios - Raw value for enum case must be a literal

Question

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

Answer 1

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.