Use notifications rather than querying state to allow Tweaks to be us…

…ed in app extensions.

FBTweak/FBTweakShakeWindow.m

@@ -17,6 +17,35 @@
 
 @implementation FBTweakShakeWindow {
   BOOL _shaking;
+  BOOL _active;
+}
+
+- (instancetype)initWithFrame:(CGRect)frame
+{
+  if ((self = [super initWithFrame:frame])) {
+    // Maintain this state manually using notifications so Tweaks can be used in app extensions, where UIApplication is unavailable.
+    _active = YES;
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_applicationWillResignActiveWithNotification:) name:UIApplicationWillResignActiveNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_applicationDidBecomeActiveWithNotification:) name:UIApplicationDidBecomeActiveNotification object:nil];
+  }
+
+  return self;
+}
+
+- (void)dealloc
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillResignActiveNotification object:nil];
+  [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];
+}
+
+- (void)_applicationWillResignActiveWithNotification:(NSNotification *)notification
+{
+  _active = NO;
+}
+
+- (void)_applicationDidBecomeActiveWithNotification:(NSNotification *)notification
+{
+  _active = YES;
 }
 
 - (void)tweakViewControllerPressedDone:(FBTweakViewController *)tweakViewController
@@ -46,7 +75,7 @@ - (BOOL)_shouldPresentTweaks
 #if TARGET_IPHONE_SIMULATOR && FB_TWEAK_ENABLED
   return YES;
 #elif FB_TWEAK_ENABLED
-  return _shaking && [[UIApplication sharedApplication] applicationState] == UIApplicationStateActive;
+  return _shaking && _active;
 #else
   return NO;
 #endif