Hi Muthu.
Thanks for the suggestion.
I don’t want to do that because failure to create the AudioQueue should mean
failure to create the AudioPlayer itself.
-Kenny
> On Sep 25, 2017, at 6:33 PM, somu subscribe <somu.subscr...@gmail.com> wrote:
>
> Hi Kenny,
>
> You could use a lazy var and initialise it with a closure.
>
> class PDAudioPlayer {
>
> //Would be created lazily when first invoked
> lazy var mQueue : AudioQueueRef = {
>
> //create an audioQueue and return that instance
> return audioQueue
> }()
> }
>
> Thanks and regards,
> Muthu
>
>
>> On 26 Sep 2017, at 9:12 AM, Kenny Leung via swift-users
>> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
>>
>> Hi All.
>>
>> I’m trying to implement the AudioQueue example from Apple in Swift, and keep
>> it as Swifty as I can. I’ve run into a problem where I have a let ivar for
>> the AudioQueue, but the only way to initialize that let ivar is to pass a
>> block to the function that creates the AudioQueue. I get the error,
>> "Variable 'self.mQueue' used before being initialized”. Is there any way to
>> get around this catch?
>>
>> Thanks!
>>
>> -Kenny
>>
>> The code follows.
>>
>> ———8<————8<————
>> class PDAudioPlayer {
>> static let kNumberBuffers :Int = 3 // 1
>> //var mDataFormat:AudioStreamBasicDescription // 2
>> let mQueue :AudioQueueRef // 3
>> //var mBuffers :[AudioQueueBufferRef] // 4
>> //var mAudioFile :AudioFileID? // 5
>> var bufferByteSize :UInt32? // 6
>> var mCurrentPacket :Int64? // 7
>> var mNumPacketsToRead :UInt32? // 8
>> var mPacketDescs :UnsafePointer<AudioStreamPacketDescription>? // 9
>> var mIsRunning: Bool = false // 10
>>
>> let dispatchQueue :DispatchQueue
>> let source :PDFileAudioSource
>> var audioBuffers :[PDAudioBuffer]
>>
>> init?(source:PDFileAudioSource) {
>> self.source = source
>> self.dispatchQueue = DispatchQueue(label:"AudioPlayer",
>> qos:.default, attributes:[], autoreleaseFrequency:.workItem, target:nil)
>> self.audioBuffers = [PDAudioBuffer]()
>>
>> var tempAudioQueue :AudioQueueRef?
>> var dataFormat = source.mDataFormat
>> let status = AudioQueueNewOutputWithDispatchQueue(&tempAudioQueue,
>> &dataFormat, 0, self.dispatchQueue) { [weak self] (queue, buffer) in //
>> ERROR on this line
>> guard let this = self else {
>> return // block
>> }
>> guard let audioBuffer =
>> this.audioBufferForAudioQueueBuffer(aqBuffer:buffer) else {
>> return // block
>> }
>> this.source.fillBuffer(audioBuffer)
>> }
>> if status != 0 {
>> return nil
>> }
>> guard let audioQueue = tempAudioQueue else {
>> return nil
>> }
>> self.mQueue = audioQueue
>> }
>>
>> private func
>> audioBufferForAudioQueueBuffer(aqBuffer:AudioQueueBufferRef) ->
>> PDAudioBuffer? {
>> for buffer in self.audioBuffers {
>> if buffer.audioQueueBuffer == aqBuffer {
>> return buffer
>> }
>> }
>> return nil
>> }
>> }
>>
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>> swift-users@swift.org <mailto:swift-users@swift.org>
>> https://lists.swift.org/mailman/listinfo/swift-users
>
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