Swift 2.0: Type of Expression is ambiguous without more context?

Question

The following used to work in Swift 1.2:

var recordSettings = [
    AVFormatIDKey: kAudioFormatMPEG4AAC,
    AVEncoderAudioQualityKey : AVAudioQuality.Max.rawValue,
    AVEncoderBitRateKey : 320000,
    AVNumberOfChannelsKey: 2,
    AVSampleRateKey : 44100.0]

Now, it gives the error:

"Type expression is ambiguous without more context".

Solution 1

To comply to the required [String : AnyObject] format required by recordSettings parameter; In addition to @Unheilig's answer, you'll need to convert your ints and floats to NSNumber:

let recordSettings : [String : AnyObject] =
[
    AVFormatIDKey: NSNumber(unsignedInt: kAudioFormatMPEG4AAC),
    AVEncoderAudioQualityKey : AVAudioQuality.Max.rawValue as NSNumber,
    AVEncoderBitRateKey : 320000 as NSNumber,
    AVNumberOfChannelsKey: 2 as NSNumber,
    AVSampleRateKey : 44100.0 as NSNumber
]

Solution 2

You could give the compiler more information:

let recordSettings : [String : Any] =
[
    AVFormatIDKey: kAudioFormatMPEG4AAC,
    AVEncoderAudioQualityKey : AVAudioQuality.Max.rawValue,
    AVEncoderBitRateKey : 320000,
    AVNumberOfChannelsKey: 2,
    AVSampleRateKey : 44100.0
]

Solution 3

I also got this error message trying to initialise an array of optionals with nil:

var eggs : [Egg] = Array<Egg>(count: 10, repeatedValue: nil)

Expression Type 'Array<Egg>' is ambiguous without more context.

Changing [Egg] to [Egg?] fixed the error.

Comments

[lernerbot]

Thank you for this. I didn't Know Any was available. I was trying AnyObject and that didn't work. Sadly the receiver of recordSettings requires [String : AnyObject]

[Stephan]

@lernerbot, see my answer below.

[lernerbot]

I agree except I didn't ask the question correctly. @Stephan answered the question I meant to ask.

[ZAFAR007]

Hi Unheilig, Can you please check my question i have same issue? Thanks http://stackoverflow.com/questions/38279942/type-of-expressi‌​on-is-ambiguous-with‌​out-more-context-swi‌​ft-2-0