Fix crashes on old MacOS versions

README.md

@@ -16,7 +16,7 @@ Initially, represented a fork of the [Flutter-WebRTC] plugin, but at the moment,
 
 ## Supported platforms
 
-- [macOS] 10.11+
+- [macOS] 10.13+
 - [Linux] (with [PulseAudio] and [X11] for screen sharing)
 - [Windows] 7+
 - [Android] 24+

crates/libwebrtc-sys/build.rs

@@ -35,6 +35,13 @@ fn main() -> anyhow::Result<()> {
         fs::create_dir_all(&lib_dir)?;
     }
     download_libwebrtc()?;
+
+    #[cfg(target_os = "macos")]
+    {
+        println!("cargo:rustc-env=MACOSX_DEPLOYMENT_TARGET=10.13");
+        env::set_var("MACOSX_DEPLOYMENT_TARGET", "10.13");
+    }
+
     compile_openal()?;
 
     let path = PathBuf::from(env::var("CARGO_MANIFEST_DIR")?);
@@ -72,7 +79,6 @@ fn main() -> anyhow::Result<()> {
     }
     #[cfg(target_os = "macos")]
     {
-        println!("cargo:rustc-env=MACOSX_DEPLOYMENT_TARGET=10.11");
         build
             .include(libpath.join("include/sdk/objc/base"))
             .include(libpath.join("include/sdk/objc"));
@@ -480,6 +486,13 @@ fn link_libs() -> anyhow::Result<()> {
         ] {
             println!("cargo:rustc-link-lib=framework={framework}");
         }
+        // AVFoundation framework needs to be weakly linked due to the usage of
+        // new APIs in libwebrtc-sys that are not available on older systems. If
+        // AVFoundation is linked strongly, dyld on application start may crash
+        // the application because it cannot link the new API symbols on the
+        // older MacOS system.
+        println!("cargo:rustc-link-arg=-weak_framework");
+        println!("cargo:rustc-link-arg=AVFoundation");
         if let Some(path) = macos_link_search_path() {
             println!("cargo:rustc-link-lib=clang_rt.osx");
             println!("cargo:rustc-link-search={path}");

crates/libwebrtc-sys/src/cpp/bridge.cc

@@ -34,7 +34,7 @@ TrackEventObserver::TrackEventObserver(
 // is attached to, has its state changed.
 void TrackEventObserver::OnChanged() {
   if (track_) {
-    if (track_.value()->state() ==
+    if ((*track_)->state() ==
         webrtc::MediaStreamTrackInterface::TrackState::kEnded) {
       bridge::on_ended(*cb_);
     }

crates/libwebrtc-sys/src/cpp/device_info_mac.mm

@@ -14,6 +14,8 @@
 DeviceInfoMac::~DeviceInfoMac() {}
 
 uint32_t DeviceInfoMac::NumberOfDevices() {
+  NSArray<AVCaptureDevice*>* devices;
+  if (@available(macOS 10.15, *)) {
   AVCaptureDeviceDiscoverySession* discoverySession =
       [AVCaptureDeviceDiscoverySession
           discoverySessionWithDeviceTypes:@[
@@ -23,7 +25,11 @@
           mediaType:AVMediaTypeVideo
           position:AVCaptureDevicePositionUnspecified];
 
-  NSArray<AVCaptureDevice*>* devices = discoverySession.devices;
+    devices = discoverySession.devices;
+  } else {
+    devices =
+      [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
+  }
 
   return [devices count];
 }
@@ -40,16 +46,21 @@
                                      uint32_t deviceUniqueIdUTF8Length,
                                      char* /*productUniqueIdUTF8*/,
                                      uint32_t /*productUniqueIdUTF8Length*/) {
-  AVCaptureDeviceDiscoverySession* discoverySession =
-      [AVCaptureDeviceDiscoverySession
-          discoverySessionWithDeviceTypes:@[
-            AVCaptureDeviceTypeBuiltInWideAngleCamera,
-            AVCaptureDeviceTypeExternalUnknown
-          ]
-          mediaType:AVMediaTypeVideo
-          position:AVCaptureDevicePositionUnspecified];
+  NSArray<AVCaptureDevice*>* devices;
+  if (@available(macOS 10.15, *)) {
+    AVCaptureDeviceDiscoverySession* discoverySession =
+        [AVCaptureDeviceDiscoverySession
+            discoverySessionWithDeviceTypes:@[
+              AVCaptureDeviceTypeBuiltInWideAngleCamera,
+              AVCaptureDeviceTypeExternalUnknown
+            ]
+            mediaType:AVMediaTypeVideo
+            position:AVCaptureDevicePositionUnspecified];
+    devices = discoverySession.devices;
+  } else {
+    devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
+  }
 
-  NSArray<AVCaptureDevice*>* devices = discoverySession.devices;
   AVCaptureDevice* device = devices[deviceNumber];
   deviceNameLength = [device.localizedName length];
   memset(deviceNameUTF8, 0, deviceNameLength);

crates/libwebrtc-sys/src/cpp/mac_capturer.mm

@@ -38,8 +38,8 @@ - (void)capturer:(RTCVideoCapturer*)capturer didCaptureVideoFrame:(RTCVideoFrame
   int currentDiff = INT_MAX;
   for (AVCaptureDeviceFormat* format in formats) {
     CMVideoDimensions dimension = CMVideoFormatDescriptionGetDimensions(format.formatDescription);
-    int diff = std::abs((int64_t)width - dimension.width) +
-               std::abs((int64_t)height - dimension.height);
+    int diff =
+        std::abs((int64_t)width - dimension.width) + std::abs((int64_t)height - dimension.height);
     if (diff < currentDiff) {
       selectedFormat = format;
       currentDiff = diff;
@@ -76,16 +76,20 @@ - (void)capturer:(RTCVideoCapturer*)capturer didCaptureVideoFrame:(RTCVideoFrame
                                                     size_t height,
                                                     size_t target_fps,
                                                     uint32_t capture_device_index) {
-  AVCaptureDeviceDiscoverySession* discoverySession =
-      [AVCaptureDeviceDiscoverySession
-          discoverySessionWithDeviceTypes:@[
-            AVCaptureDeviceTypeBuiltInWideAngleCamera,
-            AVCaptureDeviceTypeExternalUnknown
-          ]
-          mediaType:AVMediaTypeVideo
-          position:AVCaptureDevicePositionUnspecified];
-
-  NSArray<AVCaptureDevice*>* devices = discoverySession.devices;
+  NSArray<AVCaptureDevice*>* devices;
+  if (@available(macOS 10.15, *)) {
+    AVCaptureDeviceDiscoverySession* discoverySession = [AVCaptureDeviceDiscoverySession
+        discoverySessionWithDeviceTypes:@[
+          AVCaptureDeviceTypeBuiltInWideAngleCamera, AVCaptureDeviceTypeExternalUnknown
+        ]
+                              mediaType:AVMediaTypeVideo
+                               position:AVCaptureDevicePositionUnspecified];
+    devices = discoverySession.devices;
+  }
+  else {
+    devices = [RTCCameraVideoCapturer captureDevices];
+  }
+
   AVCaptureDevice* device = [devices objectAtIndex:capture_device_index];
   if (!device) {
     RTC_LOG(LS_ERROR) << "Failed to create MacCapture";

crates/libwebrtc-sys/src/cpp/video_sink.cc

@@ -10,7 +10,7 @@ ForwardingVideoSink::ForwardingVideoSink(
 
 // Propagates the received `VideoFrame` to the Rust side.
 void ForwardingVideoSink::OnFrame(const webrtc::VideoFrame& video_frame) {
-  bridge::on_frame(*cb_.value(),
+  bridge::on_frame(**cb_,
                    std::make_unique<webrtc::VideoFrame>(video_frame));
 }
 

crates/native/build.rs

@@ -7,7 +7,8 @@ use std::{env, path::PathBuf, process};
 fn main() -> anyhow::Result<()> {
     #[cfg(target_os = "macos")]
     {
-        println!("cargo:rustc-env=MACOSX_DEPLOYMENT_TARGET=10.11");
+        println!("cargo:rustc-env=MACOSX_DEPLOYMENT_TARGET=10.13");
+        env::set_var("MACOSX_DEPLOYMENT_TARGET", "10.13");
         println!("cargo:rustc-link-arg=-Wl,-undefined,dynamic_lookup");
         println!(
             "cargo:rustc-link-arg=-Wl,-install_name,\
@@ -39,7 +40,13 @@ fn main() -> anyhow::Result<()> {
 #[cfg(target_os = "macos")]
 /// Emits all the required `rustc-link-lib` instructions.
 fn link_libs() {
-    println!("cargo:rustc-link-lib=framework=AVFoundation");
+    // AVFoundation framework needs to be weakly linked due to the usage of
+    // new APIs in libwebrtc-sys that are not available on older systems. If
+    // AVFoundation is linked strongly, dyld on application start may crash
+    // the application because it cannot link the new API symbols on the
+    // older MacOS system.
+    println!("cargo:rustc-link-arg=-weak_framework");
+    println!("cargo:rustc-link-arg=AVFoundation");
     if let Some(path) = macos_link_search_path() {
         println!("cargo:rustc-link-lib=clang_rt.osx");
         println!("cargo:rustc-link-search={path}");

example/macos/Podfile.lock

@@ -19,4 +19,4 @@ SPEC CHECKSUMS:
 
 PODFILE CHECKSUM: 353c8bcc5d5b0994e508d035b5431cfe18c1dea7
 
-COCOAPODS: 1.14.3
+COCOAPODS: 1.14.2