Modifies SDK and iOS detection for helper method that needs iOS 9+

webrtc/modules/utility/source/helpers_ios.mm

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #if defined(WEBRTC_IOS)
 
 #import <AVFoundation/AVFoundation.h>
 #import <Foundation/Foundation.h>
 #import <sys/sysctl.h>
 #import <UIKit/UIKit.h>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/scoped_ptr.h"
 #include "webrtc/modules/utility/include/helpers_ios.h"
 
 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.
   struct {
     const char* raw_name;
     const char* real_name;
   } device_names[] = {
       {"iPhone1,1", "iPhone 1G"},
       {"iPhone1,2", "iPhone 3G"},
       {"iPhone2,1", "iPhone 3GS"},
@@ skipping 83 matching lines @@
 std::string GetAudioSessionCategory() {
   NSString* category = [[AVAudioSession sharedInstance] category];
   return StdStringFromNSString(category);
 }
 
 std::string GetSystemName() {
   NSString* osName = [[UIDevice currentDevice] systemName];
   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() {
   NSString* deviceModel = [[UIDevice currentDevice] model];
   return StdStringFromNSString(deviceModel);
 }
 
 std::string GetDeviceName() {
   size_t size;
   sysctlbyname("hw.machine", NULL, &size, NULL, 0);
@@ skipping 15 matching lines @@
 std::string GetOSVersionString() {
   NSString* osVersion =
       [NSProcessInfo processInfo].operatingSystemVersionString;
   return StdStringFromNSString(osVersion);
 }
 
 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
 
 #endif  // defined(WEBRTC_IOS)