feat(ios): add AVAudioSession integration and refactor implementation (#1026)

* feat: add AVAudioSession integration for iOS device enumeration and buffer size

- Use AVAudioSession for device capabilities and buffer size control
- Support BufferSize::Fixed via setPreferredIOBufferDuration
- Query buffer size from both AVAudioSession and RemoteIO for accuracy
- Update supported config queries to reflect AVAudioSession state
- Refactor input/output callbacks to use shared buffer extraction

* perf: inline performance-critical CoreAudio functions

* refactor: simplify iOS CoreAudio error handling

- Simplify error handling for device and stream config queries.
- Remove unnecessary AudioUnit buffer size queries; use AVAudioSession.
- Rename buffer size configuration function for clarity.

Author: roderickvd

CHANGELOG.md

@@ -23,6 +23,7 @@
 - CoreAudio: Configure device buffer to ensure predictable callback buffer sizes.
 - CoreAudio: Fix timestamp accuracy.
 - iOS: Fix example by properly activating audio session.
+- iOS: Add complete AVAudioSession integration for device enumeration and buffer size control.
 - WASAPI: Expose `IMMDevice` from WASAPI host Device.
 - WASAPI: Add `I24` and `U24` sample format support (24-bit samples stored in 4 bytes).
 - WASAPI: Update `windows` to >= 0.58, <= 0.62.

Cargo.toml

@@ -54,10 +54,8 @@ libc = "0.2"
 audio_thread_priority = { version = "0.34.0", optional = true }
 jack = { version = "0.13.0", optional = true }
 
-[target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
-mach2 = "0.5" # For access to mach_timebase type.
-
 [target.'cfg(target_vendor = "apple")'.dependencies]
+mach2 = "0.5"
 coreaudio-rs = { version = "0.13.0", default-features = false, features = [
     "core_audio",
     "audio_toolbox",
@@ -82,6 +80,12 @@ objc2-core-foundation = { version = "0.3.1" }
 objc2-foundation = { version = "0.3.1" }
 objc2 = { version = "0.6.2" }
 
+[target.'cfg(target_os = "ios")'.dependencies]
+objc2-avf-audio = { version = "0.3.1", default-features = false, features = [
+    "std",
+    "AVAudioSession",
+] }
+
 [target.'cfg(target_os = "emscripten")'.dependencies]
 wasm-bindgen = { version = "0.2.89" }
 wasm-bindgen-futures = "0.4.33"

src/host/coreaudio/ios/enumerate.rs

@@ -12,8 +12,8 @@ pub type SupportedOutputConfigs = ::std::vec::IntoIter<SupportedStreamConfigRang
 pub struct Devices(VecIntoIter<Device>);
 
 impl Devices {
-    pub fn new() -> Result<Self, DevicesError> {
-        Ok(Self::default())
+    pub fn new() -> Self {
+        Self::default()
     }
 }