handle hiding/showing the navigation bar properly when moving between screen that have a transparent navigation bar and ones that have visible bars. (#609)

ios/RCCViewController.m

 
 - (instancetype)initWithProps:(NSDictionary *)props children:(NSArray *)children globalProps:(NSDictionary *)globalProps bridge:(RCTBridge *)bridge
 {
-  NSString *component = props[@"component"];
-  if (!component) return nil;
-
-  NSDictionary *passProps = props[@"passProps"];
-  NSDictionary *navigatorStyle = props[@"style"];
-
-  NSMutableDictionary *mergedProps = [NSMutableDictionary dictionaryWithDictionary:globalProps];
-  [mergedProps addEntriesFromDictionary:passProps];
-  
-  RCTRootView *reactView = [[RCTRootView alloc] initWithBridge:bridge moduleName:component initialProperties:mergedProps];
-  if (!reactView) return nil;
-
-  self = [super init];
-  if (!self) return nil;
-
-  [self commonInit:reactView navigatorStyle:navigatorStyle props:props];
-
-  return self;
+    NSString *component = props[@"component"];
+    if (!component) return nil;
+    
+    NSDictionary *passProps = props[@"passProps"];
+    NSDictionary *navigatorStyle = props[@"style"];
+    
+    NSMutableDictionary *mergedProps = [NSMutableDictionary dictionaryWithDictionary:globalProps];
+    [mergedProps addEntriesFromDictionary:passProps];
+    
+    RCTRootView *reactView = [[RCTRootView alloc] initWithBridge:bridge moduleName:component initialProperties:mergedProps];
+    if (!reactView) return nil;
+    
+    self = [super init];
+    if (!self) return nil;
+    
+    [self commonInit:reactView navigatorStyle:navigatorStyle props:props];
+    
+    return self;
 }
 
 - (instancetype)initWithComponent:(NSString *)component passProps:(NSDictionary *)passProps navigatorStyle:(NSDictionary*)navigatorStyle globalProps:(NSDictionary *)globalProps bridge:(RCTBridge *)bridge
 {
-  NSMutableDictionary *mergedProps = [NSMutableDictionary dictionaryWithDictionary:globalProps];
-  [mergedProps addEntriesFromDictionary:passProps];
-  
-  RCTRootView *reactView = [[RCTRootView alloc] initWithBridge:bridge moduleName:component initialProperties:mergedProps];
-  if (!reactView) return nil;
-
-  self = [super init];
-  if (!self) return nil;
-
-  [self commonInit:reactView navigatorStyle:navigatorStyle props:passProps];
-
-  return self;
+    NSMutableDictionary *mergedProps = [NSMutableDictionary dictionaryWithDictionary:globalProps];
+    [mergedProps addEntriesFromDictionary:passProps];
+    
+    RCTRootView *reactView = [[RCTRootView alloc] initWithBridge:bridge moduleName:component initialProperties:mergedProps];
+    if (!reactView) return nil;
+    
+    self = [super init];
+    if (!self) return nil;
+    
+    [self commonInit:reactView navigatorStyle:navigatorStyle props:passProps];
+    
+    return self;
 }
 
 - (void)commonInit:(RCTRootView*)reactView navigatorStyle:(NSDictionary*)navigatorStyle props:(NSDictionary*)props
 {
-  self.view = reactView;
-  
-  self.edgesForExtendedLayout = UIRectEdgeNone; // default
-  self.automaticallyAdjustsScrollViewInsets = NO; // default
-  
-  self.navigatorStyle = [NSMutableDictionary dictionaryWithDictionary:navigatorStyle];
-  
-  [self setStyleOnInit];
-  
-  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onRNReload) name:RCTReloadNotification object:nil];
-  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onCancelReactTouches) name:RCCViewControllerCancelReactTouchesNotification object:nil];
-  
-  // In order to support 3rd party native ViewControllers, we support passing a class name as a prop mamed `ExternalNativeScreenClass`
-  // In this case, we create an instance and add it as a child ViewController which preserves the VC lifecycle.
-  // In case some props are necessary in the native ViewController, the ExternalNativeScreenProps can be used to pass them
-  [self addExternalVCIfNecessary:props];
+    self.view = reactView;
+    
+    self.edgesForExtendedLayout = UIRectEdgeNone; // default
+    self.automaticallyAdjustsScrollViewInsets = NO; // default
+    
+    self.navigatorStyle = [NSMutableDictionary dictionaryWithDictionary:navigatorStyle];
+    
+    [self setStyleOnInit];
+    
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onRNReload) name:RCTReloadNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onCancelReactTouches) name:RCCViewControllerCancelReactTouchesNotification object:nil];
+    
+    // In order to support 3rd party native ViewControllers, we support passing a class name as a prop mamed `ExternalNativeScreenClass`
+    // In this case, we create an instance and add it as a child ViewController which preserves the VC lifecycle.
+    // In case some props are necessary in the native ViewController, the ExternalNativeScreenProps can be used to pass them
+    [self addExternalVCIfNecessary:props];
 }
 
 - (void)dealloc
 
 -(void)onCancelReactTouches
 {
-  if ([self.view isKindOfClass:[RCTRootView class]]){
-    [(RCTRootView*)self.view cancelTouches];
-  }
+    if ([self.view isKindOfClass:[RCTRootView class]]){
+        [(RCTRootView*)self.view cancelTouches];
+    }
 }
 
 - (void)viewWillAppear:(BOOL)animated
 // we want to reset the style to what we expect (so we need to reset on every willAppear)
 - (void)setStyleOnAppear
 {
-  [self setStyleOnAppearForViewController:self];
+    [self setStyleOnAppearForViewController:self];
 }
 
 -(void)setStyleOnAppearForViewController:(UIViewController*)viewController
         UIColor *color = screenBackgroundColor != (id)[NSNull null] ? [RCTConvert UIColor:screenBackgroundColor] : nil;
         self.view.backgroundColor = color;
     }
- 
+    
     NSString *navBarBackgroundColor = self.navigatorStyle[@"navBarBackgroundColor"];
     if (navBarBackgroundColor)
     {
     
     NSNumber *navBarTransparent = self.navigatorStyle[@"navBarTransparent"];
     BOOL navBarTransparentBool = navBarTransparent ? [navBarTransparent boolValue] : NO;
-    if (navBarTransparentBool)
-    {
-        if (![viewController.navigationController.navigationBar viewWithTag:TRANSPARENT_NAVBAR_TAG])
+    
+    void (^action)() = ^ {
+        if (navBarTransparentBool)
         {
-            [self storeOriginalNavBarImages];
-            
-            [viewController.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
-            viewController.navigationController.navigationBar.shadowImage = [UIImage new];
-            UIView *transparentView = [[UIView alloc] initWithFrame:CGRectZero];
-            transparentView.tag = TRANSPARENT_NAVBAR_TAG;
-            [viewController.navigationController.navigationBar insertSubview:transparentView atIndex:0];
+            if (![viewController.navigationController.navigationBar viewWithTag:TRANSPARENT_NAVBAR_TAG])
+            {
+                [self storeOriginalNavBarImages];
+                
+                [viewController.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
+                viewController.navigationController.navigationBar.shadowImage = [UIImage new];
+                UIView *transparentView = [[UIView alloc] initWithFrame:CGRectZero];
+                transparentView.tag = TRANSPARENT_NAVBAR_TAG;
+                [viewController.navigationController.navigationBar insertSubview:transparentView atIndex:0];
+            }
         }
-    }
-    else
-    {
-        UIView *transparentView = [viewController.navigationController.navigationBar viewWithTag:TRANSPARENT_NAVBAR_TAG];
-        if (transparentView)
+        else
         {
-            [transparentView removeFromSuperview];
-            [viewController.navigationController.navigationBar setBackgroundImage:self.originalNavBarImages[@"bgImage"] forBarMetrics:UIBarMetricsDefault];
-            viewController.navigationController.navigationBar.shadowImage = self.originalNavBarImages[@"shadowImage"];
-            self.originalNavBarImages = nil;
+            UIView *transparentView = [viewController.navigationController.navigationBar viewWithTag:TRANSPARENT_NAVBAR_TAG];
+            if (transparentView)
+            {
+                [transparentView removeFromSuperview];
+                [viewController.navigationController.navigationBar setBackgroundImage:self.originalNavBarImages[@"bgImage"] forBarMetrics:UIBarMetricsDefault];
+                viewController.navigationController.navigationBar.shadowImage = self.originalNavBarImages[@"shadowImage"];
+                self.originalNavBarImages = nil;
+            }
         }
+    };
+    
+    if(self.transitionCoordinator.initiallyInteractive || !navBarTransparentBool) {
+        action();
+    } else {
+        UIView* backgroundView = [self.navigationController.navigationBar valueForKey:@"backgroundView"];
+        CGFloat originalAlpha = backgroundView.alpha;
+        backgroundView.alpha = navBarTransparentBool ? 0.0 : 1.0;
+        [self.transitionCoordinator animateAlongsideTransition:nil completion:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
+            action();
+            backgroundView.alpha = originalAlpha;
+        }];
     }
     
     NSNumber *navBarTranslucent = self.navigatorStyle[@"navBarTranslucent"];
     {
         self.navBarHairlineImageView.hidden = NO;
     }
-  
+    
     //Bug fix: in case there is a interactivePopGestureRecognizer, it prevents react-native from getting touch events on the left screen area that the gesture handles
     //overriding the delegate of the gesture prevents this from happening while keeping the gesture intact (another option was to disable it completely by demand)
     self.originalInteractivePopGestureDelegate = nil;
     if (self.navigationController != nil && self.navigationController.interactivePopGestureRecognizer != nil)
     {
-      id <UIGestureRecognizerDelegate> interactivePopGestureRecognizer = self.navigationController.interactivePopGestureRecognizer.delegate;
-      if (interactivePopGestureRecognizer != nil)
-      {
-        self.originalInteractivePopGestureDelegate = interactivePopGestureRecognizer;
-        self.navigationController.interactivePopGestureRecognizer.delegate = self;
-      }
+        id <UIGestureRecognizerDelegate> interactivePopGestureRecognizer = self.navigationController.interactivePopGestureRecognizer.delegate;
+        if (interactivePopGestureRecognizer != nil)
+        {
+            self.originalInteractivePopGestureDelegate = interactivePopGestureRecognizer;
+            self.navigationController.interactivePopGestureRecognizer.delegate = self;
+        }
     }
 }
 
 -(void)setStyleOnDisappear
 {
     self.navBarHairlineImageView.hidden = NO;
-  
+    
     if (self.navigationController != nil && self.navigationController.interactivePopGestureRecognizer != nil && self.originalInteractivePopGestureDelegate != nil)
     {
-      self.navigationController.interactivePopGestureRecognizer.delegate = self.originalInteractivePopGestureDelegate;
-      self.originalInteractivePopGestureDelegate = nil;
+        self.navigationController.interactivePopGestureRecognizer.delegate = self.originalInteractivePopGestureDelegate;
+        self.originalInteractivePopGestureDelegate = nil;
     }
 }
 
 
 -(void)addExternalVCIfNecessary:(NSDictionary*)props
 {
-  NSString *externalScreenClass = props[@"externalNativeScreenClass"];
-  if (externalScreenClass != nil)
-  {
-    Class class = NSClassFromString(externalScreenClass);
-    if (class != NULL)
-    {
-      id obj = [[class alloc] init];
-      if (obj != nil && [obj isKindOfClass:[UIViewController class]] && [obj conformsToProtocol:@protocol(RCCExternalViewControllerProtocol)])
-      {
-        ((id <RCCExternalViewControllerProtocol>)obj).controllerDelegate = self;
-        [obj setProps:props[@"externalNativeScreenProps"]];
-        
-        UIViewController *viewController = (UIViewController*)obj;
-        [self addChildViewController:viewController];
-        viewController.view.frame = self.view.bounds;
-        [self.view addSubview:viewController.view];
-        [viewController didMoveToParentViewController:self];
-      }
-      else
-      {
-        NSLog(@"addExternalVCIfNecessary: could not create instance. Make sure that your class is a UIViewController whihc confirms to RCCExternalViewControllerProtocol");
-      }
-    }
-    else
+    NSString *externalScreenClass = props[@"externalNativeScreenClass"];
+    if (externalScreenClass != nil)
     {
-      NSLog(@"addExternalVCIfNecessary: could not create class from string. Check that the proper class name wass passed in ExternalNativeScreenClass");
+        Class class = NSClassFromString(externalScreenClass);
+        if (class != NULL)
+        {
+            id obj = [[class alloc] init];
+            if (obj != nil && [obj isKindOfClass:[UIViewController class]] && [obj conformsToProtocol:@protocol(RCCExternalViewControllerProtocol)])
+            {
+                ((id <RCCExternalViewControllerProtocol>)obj).controllerDelegate = self;
+                [obj setProps:props[@"externalNativeScreenProps"]];
+                
+                UIViewController *viewController = (UIViewController*)obj;
+                [self addChildViewController:viewController];
+                viewController.view.frame = self.view.bounds;
+                [self.view addSubview:viewController.view];
+                [viewController didMoveToParentViewController:self];
+            }
+            else
+            {
+                NSLog(@"addExternalVCIfNecessary: could not create instance. Make sure that your class is a UIViewController whihc confirms to RCCExternalViewControllerProtocol");
+            }
+        }
+        else
+        {
+            NSLog(@"addExternalVCIfNecessary: could not create class from string. Check that the proper class name wass passed in ExternalNativeScreenClass");
+        }
     }
-  }
 }
 
 #pragma mark - NewRelic
 
 - (NSString*) customNewRelicInteractionName
 {
-  NSString *interactionName = nil;
-  
-  if (self.view != nil && [self.view isKindOfClass:[RCTRootView class]])
-  {
-    NSString *moduleName = ((RCTRootView*)self.view).moduleName;
-    if(moduleName != nil)
+    NSString *interactionName = nil;
+    
+    if (self.view != nil && [self.view isKindOfClass:[RCTRootView class]])
     {
-      interactionName = [NSString stringWithFormat:@"RCCViewController: %@", moduleName];
+        NSString *moduleName = ((RCTRootView*)self.view).moduleName;
+        if(moduleName != nil)
+        {
+            interactionName = [NSString stringWithFormat:@"RCCViewController: %@", moduleName];
+        }
     }
-  }
-  
-  if (interactionName == nil)
-  {
-    interactionName = [NSString stringWithFormat:@"RCCViewController with title: %@", self.title];
-  }
-  
-  return interactionName;
+    
+    if (interactionName == nil)
+    {
+        interactionName = [NSString stringWithFormat:@"RCCViewController with title: %@", self.title];
+    }
+    
+    return interactionName;
 }
 
+
 @end