[ios] Improved Enable/Disable statistics option code.

iphone/Maps/Settings/SettingsViewController.mm

@@ -126,8 +126,9 @@ typedef NS_ENUM(NSUInteger, Section)
   NSIndexPath * indexPath = [self.tableView indexPathForCell:cell];
   if (indexPath.section == SectionStatistics)
   {
-    [[Statistics instance] logEvent:@"StatisticsStatusChanged" withParameters:@{@"Enabled" : @(value)}];
-    Settings::Set("StatisticsEnabled", (bool)value);
+    Statistics * stat = [Statistics instance];
+    [stat logEvent:@"StatisticsStatusChanged" withParameters:@{@"Enabled" : @(value)}];
+    stat.enabled = value;
   }
   else if (indexPath.section == SectionZoomButtons)
   {

iphone/Maps/Statistics/Statistics.h

@@ -11,8 +11,8 @@
 - (void)logApiUsage:(NSString *)programName;
 - (void)logLocation:(CLLocation *)location;
 
-+ (id)instance;
++ (instancetype)instance;
 
-@property (nonatomic, readonly) BOOL enabled;
+@property (nonatomic) BOOL enabled;
 
 @end

iphone/Maps/Statistics/Statistics.mm

@@ -4,6 +4,8 @@
 
 #include "platform/settings.hpp"
 
+static constexpr char const * kStatisticsEnabledSettingsKey = "StatisticsEnabled";
+
 @implementation Statistics
 
 - (void)startSessionWithLaunchOptions:(NSDictionary *)launchOptions
@@ -58,16 +60,20 @@
 - (BOOL)enabled
 {
 #ifdef DEBUG
-  return NO;
+  bool statisticsEnabled = false;
 #else
   bool statisticsEnabled = true;
-  Settings::Get("StatisticsEnabled", statisticsEnabled);
-
-  return statisticsEnabled;
 #endif
+  (void)Settings::Get(kStatisticsEnabledSettingsKey, statisticsEnabled);
+  return statisticsEnabled;
 }
 
-+ (Statistics *)instance
+- (void)setEnabled:(BOOL)enabled
+{
+  Settings::Set(kStatisticsEnabledSettingsKey, static_cast<bool>(enabled));
+}
+
++ (instancetype)instance
 {
   static Statistics * instance;
   static dispatch_once_t onceToken;