Don't show error dialog when broadcast stops without error (Obj-C bri…

…dge) (#519)

This is an alternative to #517 that uses the same Objective-C bridge as
[used in
Telegram](https://github.com/TelegramMessenger/Telegram-iOS/blob/9a46522b431782147cc1d95304180d91d398dd82/submodules/BroadcastUploadHelpers/Sources/BroadcastUploadHelpers.m),
instead of some selector and IMP casting magic in Swift

---------

Co-authored-by: hiroshihorie <[email protected]>

Package.swift

@@ -27,12 +27,17 @@ let package = Package(
         .package(url: "https://github.com/vapor/jwt-kit.git", from: "4.13.4"),
     ],
     targets: [
+        .target(
+            name: "LKObjCHelpers",
+            publicHeadersPath: "include"
+        ),
         .target(
             name: "LiveKit",
             dependencies: [
                 .product(name: "LiveKitWebRTC", package: "webrtc-xcframework"),
                 .product(name: "SwiftProtobuf", package: "swift-protobuf"),
                 .product(name: "Logging", package: "swift-log"),
+                "LKObjCHelpers",
             ],
             resources: [
                 .process("PrivacyInfo.xcprivacy"),

Package@swift-5.9.swift

@@ -29,12 +29,17 @@ let package = Package(
         .package(url: "https://github.com/vapor/jwt-kit.git", from: "4.13.4"),
     ],
     targets: [
+        .target(
+            name: "LKObjCHelpers",
+            publicHeadersPath: "include"
+        ),
         .target(
             name: "LiveKit",
             dependencies: [
                 .product(name: "LiveKitWebRTC", package: "webrtc-xcframework"),
                 .product(name: "SwiftProtobuf", package: "swift-protobuf"),
                 .product(name: "Logging", package: "swift-log"),
+                "LKObjCHelpers",
             ],
             resources: [
                 .process("PrivacyInfo.xcprivacy"),

Sources/LKObjCHelpers/LKObjcCHelpers.m

@@ -0,0 +1,19 @@
+#import "LKObjcHelpers.h"
+
+@implementation LKObjCHelpers
+
+NS_ASSUME_NONNULL_BEGIN
+
++ (void)finishBroadcastWithoutError:(RPBroadcastSampleHandler *)handler API_AVAILABLE(macos(11.0)) {
+    // Call finishBroadcastWithError with nil error, which ends the broadcast without an error popup
+    // This is unsupported/undocumented but appears to work and is preferable to an error dialog with a cryptic default message
+    // See https://stackoverflow.com/a/63402492 for more discussion
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wnonnull"
+    [handler finishBroadcastWithError:nil];
+    #pragma clang diagnostic pop
+}
+
+NS_ASSUME_NONNULL_END
+
+@end

Sources/LKObjCHelpers/include/LKObjcHelpers.h

@@ -0,0 +1,8 @@
+#import <Foundation/Foundation.h>
+#import <ReplayKit/ReplayKit.h>
+
+@interface LKObjCHelpers : NSObject
+
++ (void)finishBroadcastWithoutError:(RPBroadcastSampleHandler *)handler API_AVAILABLE(macos(11.0));
+
+@end

Sources/LiveKit/Broadcast/Uploader/LKSampleHandler.swift

@@ -20,6 +20,8 @@
 import ReplayKit
 #endif
 
+import LKObjCHelpers
+
 open class LKSampleHandler: RPBroadcastSampleHandler {
     private var clientConnection: BroadcastUploadSocketConnection?
     private var uploader: SampleUploader?
@@ -78,18 +80,36 @@ open class LKSampleHandler: RPBroadcastSampleHandler {
         }
     }
 
+    /// Override point to change the behavior when the socket connection has closed.
+    /// The default behavior is to pass errors through, and otherwise show nothing to the user.
+    ///
+    /// You should call `finishBroadcastWithError` in your implementation, but you can
+    /// add custom logging or present a custom error to the user instead.
+    ///
+    /// To present a custom error message:
+    ///   ```
+    ///   self.finishBroadcastWithError(NSError(
+    ///     domain: RPRecordingErrorDomain,
+    ///     code: 10001,
+    ///     userInfo: [NSLocalizedDescriptionKey: "My Custom Error Message"]
+    ///   ))
+    ///   ```
+    open func connectionDidClose(error: Error?) {
+        if let error {
+            finishBroadcastWithError(error)
+        } else {
+            LKObjCHelpers.finishBroadcastWithoutError(self)
+        }
+    }
+
     private func setupConnection() {
         clientConnection?.didClose = { [weak self] error in
             logger.log(level: .debug, "client connection did close \(String(describing: error))")
-
-            if let error {
-                self?.finishBroadcastWithError(error)
-            } else {
-                // the displayed failure message is more user friendly when using NSError instead of Error
-                let LKScreenSharingStopped = 10001
-                let customError = NSError(domain: RPRecordingErrorDomain, code: LKScreenSharingStopped, userInfo: [NSLocalizedDescriptionKey: "Screen sharing stopped"])
-                self?.finishBroadcastWithError(customError)
+            guard let self else {
+                return
             }
+
+            self.connectionDidClose(error: error)
         }
     }