The following used to work in Swift 1.2:
var recordSettings = [
AVFormatIDKey: kAudioFormatMPEG4AAC,
AVEncoderAudioQualityKey : AVAudioQuality.Max.ra
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
]