From ab12c47160591ff78a92da304e143b84865d6d99 Mon Sep 17 00:00:00 2001
From: henrika <henrika@webrtc.org>
Date: Thu, 3 Mar 2016 16:59:50 +0100
Subject: [PATCH] Modifies SDK and iOS detection for helper method that needs
 iOS 9+

BUG=NONE
R=tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1746023002 .

Cr-Commit-Position: refs/heads/master@{#11861}
---
 .../audio_device/ios/audio_device_ios.mm      |  5 +++-
 webrtc/modules/utility/include/helpers_ios.h  |  9 ++++---
 webrtc/modules/utility/source/helpers_ios.mm  | 27 +++++++++++++------
 3 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/webrtc/modules/audio_device/ios/audio_device_ios.mm b/webrtc/modules/audio_device/ios/audio_device_ios.mm
index 2551dad76d..4390f49258 100644
--- a/webrtc/modules/audio_device/ios/audio_device_ios.mm
+++ b/webrtc/modules/audio_device/ios/audio_device_ios.mm
@@ -262,14 +262,17 @@ static void LogDeviceInfo() {
   LOG(LS_INFO) << "LogDeviceInfo";
   @autoreleasepool {
     LOG(LS_INFO) << " system name: " << ios::GetSystemName();
-    LOG(LS_INFO) << " system version: " << ios::GetSystemVersion();
+    LOG(LS_INFO) << " system version 1(2): " << ios::GetSystemVersionAsString();
+    LOG(LS_INFO) << " system version 2(2): " << ios::GetSystemVersion();
     LOG(LS_INFO) << " device type: " << ios::GetDeviceType();
     LOG(LS_INFO) << " device name: " << ios::GetDeviceName();
     LOG(LS_INFO) << " process name: " << ios::GetProcessName();
     LOG(LS_INFO) << " process ID: " << ios::GetProcessID();
     LOG(LS_INFO) << " OS version: " << ios::GetOSVersionString();
     LOG(LS_INFO) << " processing cores: " << ios::GetProcessorCount();
+#if defined(__IPHONE_9_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_9_0
     LOG(LS_INFO) << " low power mode: " << ios::GetLowPowerModeEnabled();
+#endif
   }
 }
 #endif  // !defined(NDEBUG)
diff --git a/webrtc/modules/utility/include/helpers_ios.h b/webrtc/modules/utility/include/helpers_ios.h
index d3f788fec3..1b692f18c1 100644
--- a/webrtc/modules/utility/include/helpers_ios.h
+++ b/webrtc/modules/utility/include/helpers_ios.h
@@ -37,11 +37,12 @@ std::string GetAudioSessionCategory();
 // Returns the current name of the operating system.
 std::string GetSystemName();
 
-// Returns the current version of the operating system.
-std::string GetSystemVersion();
+// Returns the current version of the operating system as a string.
+std::string GetSystemVersionAsString();
 
-// Returns the version of the operating system as a floating point value.
-float GetSystemVersionAsFloat();
+// Returns the version of the operating system in double representation.
+// Uses a cached value of the system version.
+double GetSystemVersion();
 
 // Returns the device type.
 // Examples: ”iPhone” and ”iPod touch”.
diff --git a/webrtc/modules/utility/source/helpers_ios.mm b/webrtc/modules/utility/source/helpers_ios.mm
index a312f032d1..3d7567b7f0 100644
--- a/webrtc/modules/utility/source/helpers_ios.mm
+++ b/webrtc/modules/utility/source/helpers_ios.mm
@@ -23,6 +23,10 @@
 namespace webrtc {
 namespace ios {
 
+bool isOperatingSystemAtLeastVersion(double version) {
+  return GetSystemVersion() >= version;
+}
+
 // Internal helper method used by GetDeviceName() to return device name.
 const char* LookUpRealName(const char* raw_name) {
   // Lookup table which maps raw device names to real (human readable) names.
@@ -126,14 +130,18 @@ std::string GetSystemName() {
   return StdStringFromNSString(osName);
 }
 
-std::string GetSystemVersion() {
+std::string GetSystemVersionAsString() {
   NSString* osVersion = [[UIDevice currentDevice] systemVersion];
   return StdStringFromNSString(osVersion);
 }
 
-float GetSystemVersionAsFloat() {
-  NSString* osVersion = [[UIDevice currentDevice] systemVersion];
-  return osVersion.floatValue;
+double GetSystemVersion() {
+  static dispatch_once_t once_token;
+  static double system_version;
+  dispatch_once(&once_token, ^{
+    system_version = [UIDevice currentDevice].systemVersion.doubleValue;
+  });
+  return system_version;
 }
 
 std::string GetDeviceType() {
@@ -169,14 +177,17 @@ int GetProcessorCount() {
   return [NSProcessInfo processInfo].processorCount;
 }
 
+#if defined(__IPHONE_9_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_9_0
 bool GetLowPowerModeEnabled() {
-  NSProcessInfo* info = [NSProcessInfo processInfo];
-  // lowPoweredModeEnabled is only available on iOS9+.
-  if ([info respondsToSelector:@selector(lowPoweredModeEnabled)]) {
-    return info.lowPowerModeEnabled;
+  if (isOperatingSystemAtLeastVersion(9.0)) {
+    // lowPoweredModeEnabled is only available on iOS9+.
+    return [NSProcessInfo processInfo].lowPowerModeEnabled;
   }
+  LOG(LS_WARNING) << "webrtc::ios::GetLowPowerModeEnabled() is not "
+                     "supported. Requires at least iOS 9.0";
   return false;
 }
+#endif
 
 }  // namespace ios
 }  // namespace webrtc