Refactor coreaudio host and add iOS support + ios-feedback example

.github/workflows/cpal.yml

@@ -135,14 +135,14 @@ jobs:
         with:
           command: check
           use-cross: true
-          args: --target armv7-unknown-linux-gnueabihf --workspace --all-features --verbose  
+          args: --target armv7-unknown-linux-gnueabihf --workspace --all-features --verbose
 
       - name: Test all features for armv7
         uses: actions-rs/cargo@v1
         with:
           command: test
           use-cross: true
-          args: --target armv7-unknown-linux-gnueabihf --workspace --all-features --verbose      
+          args: --target armv7-unknown-linux-gnueabihf --workspace --all-features --verbose
 
   asmjs-wasm32-test:
     strategy:
@@ -287,3 +287,23 @@ jobs:
       run: cargo install cargo-apk
     - name: Build APK
       run: cargo apk build --example android
+
+  ios-build:
+    runs-on: macOS-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install llvm and clang
+      run: brew install llvm
+    - name: Install stable
+      uses: actions-rs/toolchain@v1
+      with:
+        profile: minimal
+        toolchain: stable
+        override: true
+    - name: Add iOS targets
+      run: rustup target add aarch64-apple-ios x86_64-apple-ios
+    - name: Install cargo lipo
+      run: cargo install cargo-lipo
+    - name: Build iphonesimulator feedback example
+      run: cd examples/ios-feedback && xcodebuild -scheme cpal-ios-example -configuration Debug -derivedDataPath build -sdk iphonesimulator
+

Cargo.toml

@@ -35,10 +35,15 @@ parking_lot = "0.11"
 jack = { version = "0.6.5", optional = true }
 
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
-coreaudio-rs = { version = "0.9.1", default-features = false, features = ["audio_unit", "core_audio"] }
 core-foundation-sys = "0.6.2" # For linking to CoreFoundation.framework and handling device name `CFString`s.
 mach = "0.3" # For access to mach_timebase type.
 
+[target.'cfg(target_os = "macos")'.dependencies]
+coreaudio-rs = { version = "0.10.0", default-features = false, features = ["audio_unit", "core_audio"] }
+
+[target.'cfg(target_os = "ios")'.dependencies]
+coreaudio-rs = { version = "0.10.0", default-features = false, features = ["audio_unit", "core_audio", "audio_toolbox"] }
+
 [target.'cfg(target_os = "emscripten")'.dependencies]
 stdweb = { version = "0.1.3", default-features = false }
 

examples/ios-feedback/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "cpal-ios-example"
+version = "0.1.0"
+authors = ["Michael Hills <mhills@gmail.com>"]
+edition = "2018"
+
+[lib]
+name = "cpal_ios_example"
+crate-type = ["staticlib"]
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+cpal = { path = "../.." }
+anyhow = "1.0.12"
+ringbuf = "0.1.6"
+

examples/ios-feedback/README.md

@@ -0,0 +1,25 @@
+# iOS Feedback Example
+
+This example is an Xcode project that exercises both input and output
+audio streams. Audio samples are read in from your micrphone and then
+routed to your audio output device with a small but noticeable delay
+so you can verify it is working correctly.
+
+To build the example you will need to still `cargo-lipo`. While not
+necessary for building iOS binaries, it is used to build a universal
+binary (x86 for simulator and aarch64 for device.)
+
+```
+cargo install cargo-lipo
+```
+
+Then open the XCode project and click run. A hook in the iOS application
+lifecycle calls into the Rust code to start the input/output feedback
+loop and immediately returns back control.
+
+Before calling into Rust, the AVAudioSession category is configured.
+This is important for controlling how audio is shared with the rest
+of the system when your app is in the foreground. One example is
+controlling whether other apps can play music in the background.
+More information [here](https://developer.apple.com/library/archive/documentation/Audio/Conceptual/AudioSessionProgrammingGuide/AudioSessionCategoriesandModes/AudioSessionCategoriesandModes.html#//apple_ref/doc/uid/TP40007875-CH10).
+

examples/ios-feedback/build_rust_deps.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+set -e
+
+PATH=$PATH:$HOME/.cargo/bin
+
+# If you want your build to run faster, add a "--targets x86_64-apple-ios" for just using the ios simulator.
+if [ -n ${IOS_TARGETS} ]; then
+    cargo lipo --targets ${IOS_TARGETS}
+else
+    cargo lipo
+fi