Make SignalMessaging AppExtension safe

// FREEBIE

Signal.xcodeproj/project.pbxproj

@@ -3493,6 +3493,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 9B533A9FA46206D3D99C9ADA /* Pods-SignalMessaging.debug.xcconfig */;
 			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
@@ -3546,6 +3547,7 @@
 			baseConfigurationReference = 948239851C08032C842937CC /* Pods-SignalMessaging.test.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
@@ -3618,6 +3620,7 @@
 			baseConfigurationReference = 8EEE74B0753448C085B48721 /* Pods-SignalMessaging.app store release.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";

Signal/src/util/MainAppContext.m

@@ -18,6 +18,12 @@ NS_ASSUME_NONNULL_BEGIN
     return [UIApplication sharedApplication].applicationState == UIApplicationStateActive;
 }
 
+- (BOOL)isRTL
+{
+    return
+        [[UIApplication sharedApplication] userInterfaceLayoutDirection] == UIUserInterfaceLayoutDirectionRightToLeft;
+}
+
 - (UIApplicationState)mainApplicationState
 {
     return [UIApplication sharedApplication].applicationState;

SignalMessaging/categories/UIView+OWS.m

@@ -4,6 +4,7 @@
 
 #import "OWSMath.h"
 #import "UIView+OWS.h"
+#import <SignalServiceKit/AppContext.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -256,8 +257,7 @@ CGFloat ScaleFromIPhone5(CGFloat iPhone5Value)
         return ([UIView userInterfaceLayoutDirectionForSemanticContentAttribute:self.semanticContentAttribute]
             == UIUserInterfaceLayoutDirectionRightToLeft);
     } else {
-        return
-            [UIApplication sharedApplication].userInterfaceLayoutDirection == UIUserInterfaceLayoutDirectionRightToLeft;
+        return [CurrentAppContext() isRTL];
     }
 }
 

SignalServiceKit/src/Util/AppContext.h

@@ -26,6 +26,8 @@ typedef void (^BackgroundTaskExpirationHandler)(void);
 // Should only be called if isMainApp is YES.
 - (void)setMainAppBadgeNumber:(NSInteger)value;
 
+- (BOOL)isRTL;
+
 @end
 
 id<AppContext> CurrentAppContext(void);

SignalShareExtension/utils/ShareAppExtensionContext.m

@@ -18,6 +18,15 @@ NS_ASSUME_NONNULL_BEGIN
     return NO;
 }
 
+- (BOOL)isRTL
+{
+    // Borrowed from PureLayout's AppExtension compatible RTL support.
+    // App Extensions may not access -[UIApplication sharedApplication]; fall back to checking the bundle's preferred
+    // localization character direction
+    return [NSLocale characterDirectionForLanguage:[[NSBundle mainBundle] preferredLocalizations][0]]
+        == NSLocaleLanguageDirectionRightToLeft;
+}
+
 - (UIApplicationState)mainApplicationState
 {
     OWSFail(@"%@ called %s.", self.logTag, __PRETTY_FUNCTION__);