AURenderCallback in Swift

Question

I am creating an application that uses Audio Units, and although there are many sample code in Objective-C (including Apple, aurioTouch and others). I am trying to encode everything in Swift.

I was able to customize my AUGraph and run some sound through it, but I can’t figure out what syntax is for visualization callbacks. I tried several methods:

Method 1: Create an AURenderCallback Directly

let render : AURenderCallback = { (
    inRefCon: UnsafeMutablePointer<Void>,
    ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
    inTimeStamp: UnsafePointer<AudioTimeStamp>,
    inBufNumber: UInt32,
    inNumberFrames: UInt32,
    ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus in

    return noErr
}

I am not doing anything in this callback except returning noErr at the moment, as I am just trying to make it work. However, the compiler returns the following error:

(UnsafeMutablePointer, UnsafeMutablePointer, UnsafePointer, UInt32, UInt32, UnsafeMutablePointer) -> OSStatus 'is not convertible to' AURenderCallback

AURenderCallback :

typealias AURenderCallback = (UnsafeMutablePointer<Void>,UnsafeMutablePointer<AudioUnitRenderActionFlags>,UnsafePointer<AudioTimeStamp>, UInt32, UInt32,UnsafeMutablePointer<AudioBufferList>) -> OSStatus

, , , , .

2. , AURenderCallback

func render(
    inRefCon: UnsafeMutablePointer<Void>,
    ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
    inTimeStamp: UnsafePointer<AudioTimeStamp>,
    inBufNumber: UInt32,
    inNumberFrames: UInt32,
    ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus {

    return noErr
}

, AURenderCallbackStruct inputProc, :

AURenderCallbackStruct, '(inputProc: (UnsafeMutablePointer, UnsafeMutablePointer, UnsafePointer, UInt32, UInt32, UnsafeMutablePointer) → OSStatus, inputProcRefCon: )

AURenderCallbacks Swift, , , Objective-C. .

Answer 1

, ( , CoreAudio/Audio Unit Swift).

( :-)) Swift Cocoa Objective-C - . Function Pointers

, , Swift , .

. , :

func renderCallback(inRefCon:UnsafeMutablePointer<Void>,
ioActionFlags:UnsafeMutablePointer<AudioUnitRenderActionFlags>,
inTimeStamp:UnsafePointer<AudioTimeStamp>,
inBusNumber:UInt32,
inNumberFrames:UInt32,
ioData:UnsafeMutablePointer<AudioBufferList>) -> OSStatus {
    let delegate = unsafeBitCast(inRefCon, AURenderCallbackDelegate.self)
    let result = delegate.performRender(ioActionFlags,
        inTimeStamp: inTimeStamp,
        inBusNumber: inBusNumber,
        inNumberFrames: inNumberFrames,
        ioData: ioData)
    return result
}

, . ( , , : -))

@objc protocol AURenderCallbackDelegate {
func performRender(ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
    inTimeStamp: UnsafePointer<AudioTimeStamp>,
    inBusNumber: UInt32,
    inNumberFrames: UInt32,
    ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus
}

" ", AURenderCallbackDelegate :

class AudioUnitGraphManager: NSObject, AURenderCallbackDelegate

renderCallback AudioUnitGraphManager

func performRender(ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>, inTimeStamp: UnsafePointer<AudioTimeStamp>, inBusNumber: UInt32, inNumberFrames: UInt32, ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus {
    print("Hello there!")
    return noErr
}

, render notify, :

AudioUnitAddRenderNotify(mixerUnit, renderCallback, UnsafeMutablePointer(unsafeAddressOf(self)))

, .

Swift 3

Swift 3 AURenderCallback :

typealias AURenderCallback = (UnsafeMutableRawPointer, UnsafeMutablePointer<AudioUnitRenderActionFlags>, UnsafePointer<AudioTimeStamp>, UInt32, UInt32, UnsafeMutablePointer<AudioBufferList>?) -> OSStatus

, UnsafeMutablePointer<AudioBufferList>? UnsafeMutablePointer<AudioBufferList> ( ).

, .

renderCallback

func renderCallback(inRefCon:UnsafeMutablePointer<Void>,
ioActionFlags:UnsafeMutablePointer<AudioUnitRenderActionFlags>,
inTimeStamp:UnsafePointer<AudioTimeStamp>,
inBusNumber:UInt32,
inNumberFrames:UInt32,
ioData:UnsafeMutablePointer<AudioBufferList>?) -> OSStatus {
    let delegate = unsafeBitCast(inRefCon, AURenderCallbackDelegate.self)
    let result = delegate.performRender(ioActionFlags,
        inTimeStamp: inTimeStamp,
        inBusNumber: inBusNumber,
        inNumberFrames: inNumberFrames,
        ioData: ioData)
    return result
}

AURenderCallbackDelegate

@objc protocol AURenderCallbackDelegate {
func performRender(ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
    inTimeStamp: UnsafePointer<AudioTimeStamp>,
    inBusNumber: UInt32,
    inNumberFrames: UInt32,
    ioData: UnsafeMutablePointer<AudioBufferList>?) -> OSStatus
}

performRender

    func performRender(ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>, inTimeStamp: UnsafePointer<AudioTimeStamp>, inBusNumber: UInt32, inNumberFrames: UInt32, ioData: UnsafeMutablePointer<AudioBufferList>?) -> OSStatus {
    print("Hello there!")
    return noErr
}

AudioUnitAddRenderNotify(mixerUnit!, renderCallback, Unmanaged.passUnretained(self).toOpaque())