CODEWITHSUNDEEP
swift
royco
royco

Reputation: 5529

Can Swift cast a UInt to an Enum with "as"?

I'm aware of creating an Enum from a UInt using rawValue:. However, can Swift cast a UInt to an Enum using as? Here's a screenshot from the WWDC 2016 talk Delivering an Exceptional Audio Experience:

WWDC sample code casting to Enum

As you can see, the code retrieves a numeric value from the dictionary and casts it to an Enum using as!.

I haven't been able to do this in my code. Is it valid Swift?

Upvotes: 0

Views: 207

Answers (1)

Sulthan
Sulthan

Reputation: 130172

I have been trying to reproduce the code with the same enum and with my own enums and the cast always crashes as it should, in my opinion, e.g.:

let x: AVAudioSessionInterruptionType = .began
let dictionary: NSDictionary = [AVAudioSessionInterruptionTypeKey: x.rawValue as NSNumber]

// crash
let value = dictionary[AVAudioSessionInterruptionTypeKey] as! AVAudioSessionInterruptionType

I went through the Swift evolution list and I haven't found a change that could cause this to work. To be honest, not all code snippets shown in WWDC are working.

Upvotes: 1

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