Add OS Log sink for iOS

PiperOrigin-RevId: 764981349

connections/c/nc.cc

@@ -229,6 +229,7 @@ NC_INSTANCE NcCreateService() {
   absl::SetGlobalVLogLevel(1);
 #endif  // DEBUG
   ::nearby::apple::EnableNearbyLoggerWriter();
+  ::nearby::apple::EnableOsLog("com.google.nearby.connections");
 #endif  // TARGET_OS_IOS
 
 #if defined(NC_IOS_SDK)

internal/platform/implementation/apple/BUILD

@@ -164,6 +164,22 @@ objc_library(
     ],
 )
 
+objc_library(
+    name = "os_log_sink",
+    srcs = [
+        "os_log_sink.mm",
+    ],
+    hdrs = [
+        "os_log_sink.h",
+    ],
+    # Prevent Objective-C++ headers from being pulled into swift.
+    aspect_hints = ["//tools/build_defs/swift:no_module"],
+    deps = [
+        "//internal/platform:logging",
+        "@com_google_absl//absl/strings",
+    ],
+)
+
 objc_library(
     name = "logger_writer",
     srcs = [
@@ -175,6 +191,7 @@ objc_library(
     # Prevent Objective-C++ headers from being pulled into swift.
     aspect_hints = ["//tools/build_defs/swift:no_module"],
     deps = [
+        ":os_log_sink",
         "//internal/platform:logging",
         "//third_party/objective_c/google_toolbox_for_mac:GTM_Logger",
     ],

internal/platform/implementation/apple/nearby_logger_writer.h

@@ -15,6 +15,8 @@
 #ifndef PLATFORM_IMPL_APPLE_NEARBY_LOGGER_WRITER_H_
 #define PLATFORM_IMPL_APPLE_NEARBY_LOGGER_WRITER_H_
 
+#include <string>
+
 namespace nearby {
 namespace apple {
 
@@ -23,6 +25,10 @@ namespace apple {
 // connections.
 void EnableNearbyLoggerWriter();
 
+// Enables the OS log output as the given subsystem. The method should be called
+// once during the application lifetime.
+void EnableOsLog(const std::string& subsystem);
+
 }  // namespace apple
 }  // namespace nearby
 

internal/platform/implementation/apple/nearby_logger_writer.mm

@@ -17,6 +17,7 @@
 #include <cstdint>
 #include <string>
 
+#include "internal/platform/implementation/apple/os_log_sink.h"
 #include "internal/platform/logging.h"
 
 #import "GoogleToolboxForMac/GTMLogger.h"
@@ -162,6 +163,14 @@ NS_ASSUME_NONNULL_END
 
 namespace nearby {
 namespace apple {
+namespace {
+
+OsLogSink *GetOsLogSink(const std::string &subsystem) {
+  static OsLogSink *sink = new OsLogSink(subsystem);
+  return sink;
+}
+
+}  // namespace
 
 void EnableNearbyLoggerWriter() {
   NSMutableArray<NearbyLogMessage *> *tupleArray = [[NSMutableArray alloc] init];
@@ -171,5 +180,7 @@ void EnableNearbyLoggerWriter() {
                            filter:nil];
 }
 
+void EnableOsLog(const std::string &subsystem) { absl::AddLogSink(GetOsLogSink(subsystem)); }
+
 }  // namespace apple
 }  // namespace nearby

internal/platform/implementation/apple/os_log_sink.h

@@ -0,0 +1,41 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef PLATFORM_IMPL_APPLE_OS_LOG_SINK_H_
+#define PLATFORM_IMPL_APPLE_OS_LOG_SINK_H_
+
+#include <os/log.h>
+
+#include "internal/platform/logging.h"
+
+namespace nearby {
+namespace apple {
+
+// OsLogSink is a LogSink that sends logs to the OS log.
+class OsLogSink : public absl::LogSink {
+ public:
+  explicit OsLogSink(const std::string& subsystem);
+  ~OsLogSink() override = default;
+
+  // Sends the log entry to the OS log.
+  void Send(const absl::LogEntry& entry) override;
+
+ private:
+  os_log_t log_;
+};
+
+}  // namespace apple
+}  // namespace nearby
+
+#endif  // PLATFORM_IMPL_APPLE_OS_LOG_SINK_H_

internal/platform/implementation/apple/os_log_sink.mm

@@ -0,0 +1,57 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/platform/implementation/apple/os_log_sink.h"
+
+#include <os/log.h>
+
+#include "absl/strings/str_cat.h"
+#include "internal/platform/logging.h"
+
+namespace nearby {
+namespace apple {
+
+OsLogSink::OsLogSink(const std::string& subsystem)
+    : log_(os_log_create(subsystem.c_str(), "default")) {}
+
+void OsLogSink::Send(const absl::LogEntry& entry) {
+  os_log_type_t type = OS_LOG_TYPE_DEFAULT;
+  switch (entry.log_severity()) {
+    case absl::LogSeverity::kInfo:
+      type = OS_LOG_TYPE_INFO;
+      break;
+    case absl::LogSeverity::kWarning:
+      type = OS_LOG_TYPE_DEFAULT;  // OSLog doesn't have a distinct 'Warning' level
+      break;
+    case absl::LogSeverity::kError:
+      type = OS_LOG_TYPE_ERROR;
+      break;
+    case absl::LogSeverity::kFatal:
+      type = OS_LOG_TYPE_FAULT;
+      break;
+  }
+
+  if (entry.verbosity() == 1) {
+    type = OS_LOG_TYPE_DEBUG;
+  }
+
+  // Format and send the log message to OSLog.
+  std::string message = absl::StrCat("[", entry.source_basename(), ":", entry.source_line(), "] ",
+                                     entry.text_message());
+
+  os_log_with_type(log_, type, "%s", message.c_str());
+}
+
+}  // namespace apple
+}  // namespace nearby