Added lightweight generic annotations

Summary: public

Added lightweight genarics annotations to make the code more readable and help the compiler catch bugs.

Fixed some type bugs and improved bridge validation in a few places.

Reviewed By: javache

Differential Revision: D2600189

fb-gh-sync-id: f81e22f2cdc107bf8d0b15deec6d5b83aacc5b56

React/Views/RCTComponent.h

@@ -27,7 +27,7 @@ typedef void (^RCTBubblingEventBlock)(NSDictionary *body);
 
 - (void)insertReactSubview:(id<RCTComponent>)subview atIndex:(NSInteger)atIndex;
 - (void)removeReactSubview:(id<RCTComponent>)subview;
-- (NSArray *)reactSubviews;
+- (NSArray<id<RCTComponent>> *)reactSubviews;
 - (id<RCTComponent>)reactSuperview;
 - (NSNumber *)reactTagAtPoint:(CGPoint)point;
 

React/Views/RCTComponentData.m

@@ -100,7 +100,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
     SEL selector = NSSelectorFromString([NSString stringWithFormat:@"propConfig%@_%@", shadowView ? @"Shadow" : @"", name]);
     Class managerClass = [_manager class];
     if ([managerClass respondsToSelector:selector]) {
-      NSArray *typeAndKeyPath = ((NSArray *(*)(id, SEL))objc_msgSend)(managerClass, selector);
+      NSArray<NSString *> *typeAndKeyPath =
+        ((NSArray<NSString *> *(*)(id, SEL))objc_msgSend)(managerClass, selector);
       type = NSSelectorFromString([typeAndKeyPath[0] stringByAppendingString:@":"]);
       keyPath = typeAndKeyPath.count > 1 ? typeAndKeyPath[1] : nil;
     } else {
@@ -125,7 +126,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
       // Disect keypath
       NSString *key = name;
-      NSArray *parts = [keyPath componentsSeparatedByString:@"."];
+      NSArray<NSString *> *parts = [keyPath componentsSeparatedByString:@"."];
       if (parts) {
         key = parts.lastObject;
         parts = [parts subarrayWithRange:(NSRange){0, parts.count - 1}];
@@ -312,9 +313,9 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 {
   Class managerClass = [_manager class];
 
-  NSMutableArray *directEvents = [NSMutableArray new];
+  NSMutableArray<NSString *> *directEvents = [NSMutableArray new];
   if (RCTClassOverridesInstanceMethod(managerClass, @selector(customDirectEventTypes))) {
-    NSArray *events = [_manager customDirectEventTypes];
+    NSArray<NSString *> *events = [_manager customDirectEventTypes];
     if (RCT_DEBUG) {
       RCTAssert(!events || [events isKindOfClass:[NSArray class]],
         @"customDirectEventTypes must return an array, but %@ returned %@",
@@ -325,9 +326,9 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
     }
   }
 
-  NSMutableArray *bubblingEvents = [NSMutableArray new];
+  NSMutableArray<NSString *> *bubblingEvents = [NSMutableArray new];
   if (RCTClassOverridesInstanceMethod(managerClass, @selector(customBubblingEventTypes))) {
-        NSArray *events = [_manager customBubblingEventTypes];
+    NSArray<NSString *> *events = [_manager customBubblingEventTypes];
     if (RCT_DEBUG) {
       RCTAssert(!events || [events isKindOfClass:[NSArray class]],
         @"customBubblingEventTypes must return an array, but %@ returned %@",
@@ -349,7 +350,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
       NSRange nameRange = [methodName rangeOfString:@"_"];
       if (nameRange.length) {
         NSString *name = [methodName substringFromIndex:nameRange.location + 1];
-        NSString *type = ((NSArray *(*)(id, SEL))objc_msgSend)(managerClass, selector)[0];
+        NSString *type = ((NSArray<NSString *> *(*)(id, SEL))objc_msgSend)(managerClass, selector)[0];
         if (RCT_DEBUG && propTypes[name] && ![propTypes[name] isEqualToString:type]) {
           RCTLogError(@"Property '%@' of component '%@' redefined from '%@' "
                       "to '%@'", name, _name, propTypes[name], type);

React/Views/RCTMap.h

@@ -25,7 +25,7 @@ extern const CGFloat RCTMapZoomBoundBuffer;
 @property (nonatomic, assign) CGFloat maxDelta;
 @property (nonatomic, assign) UIEdgeInsets legalLabelInsets;
 @property (nonatomic, strong) NSTimer *regionChangeObserveTimer;
-@property (nonatomic, strong) NSMutableArray *annotationIds;
+@property (nonatomic, copy) NSArray<NSString *> *annotationIds;
 
 @property (nonatomic, copy) RCTBubblingEventBlock onChange;
 @property (nonatomic, copy) RCTBubblingEventBlock onPress;

React/Views/RCTMap.m

@@ -109,9 +109,9 @@ const CGFloat RCTMapZoomBoundBuffer = 0.01;
 
 - (void)setAnnotations:(RCTPointAnnotationArray *)annotations
 {
-  NSMutableArray *newAnnotationIds = [NSMutableArray new];
-  NSMutableArray *annotationsToDelete = [NSMutableArray new];
-  NSMutableArray *annotationsToAdd = [NSMutableArray new];
+  NSMutableArray<NSString *> *newAnnotationIds = [NSMutableArray new];
+  NSMutableArray<RCTPointAnnotation *> *annotationsToDelete = [NSMutableArray new];
+  NSMutableArray<RCTPointAnnotation *> *annotationsToAdd = [NSMutableArray new];
 
   for (RCTPointAnnotation *annotation in annotations) {
     if (![annotation isKindOfClass:[RCTPointAnnotation class]]) {
@@ -138,19 +138,19 @@ const CGFloat RCTMapZoomBoundBuffer = 0.01;
   }
 
   if (annotationsToDelete.count) {
-    [self removeAnnotations:annotationsToDelete];
+    [self removeAnnotations:(NSArray<id<MKAnnotation>> *)annotationsToDelete];
   }
 
   if (annotationsToAdd.count) {
-    [self addAnnotations:annotationsToAdd];
+    [self addAnnotations:(NSArray<id<MKAnnotation>> *)annotationsToAdd];
   }
 
-  NSMutableArray *newIds = [NSMutableArray new];
-  for (RCTPointAnnotation *anno in self.annotations) {
-    if ([anno isKindOfClass:[MKUserLocation class]]) {
+  NSMutableArray<NSString *> *newIds = [NSMutableArray new];
+  for (RCTPointAnnotation *annotation in self.annotations) {
+    if ([annotation isKindOfClass:[MKUserLocation class]]) {
       continue;
     }
-    [newIds addObject:anno.identifier];
+    [newIds addObject:annotation.identifier];
   }
   self.annotationIds = newIds;
 }

React/Views/RCTModalHostView.m

@@ -51,18 +51,18 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:coder)
   }
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<UIView<RCTComponent> *> *)reactSubviews
 {
-  return [NSArray arrayWithObjects:_modalViewController.view, nil];
+  return _modalViewController.view ? @[_modalViewController.view] : @[];
 }
 
-- (void)insertReactSubview:(UIView *)subview atIndex:(__unused NSInteger)atIndex
+- (void)insertReactSubview:(UIView<RCTComponent> *)subview atIndex:(__unused NSInteger)atIndex
 {
   [subview addGestureRecognizer:_touchHandler];
   _modalViewController.view = subview;
 }
 
-- (void)removeReactSubview:(UIView *)subview
+- (void)removeReactSubview:(UIView<RCTComponent> *)subview
 {
   RCTAssert(subview == _modalViewController.view, @"Cannot remove view other than modal view");
   _modalViewController.view = nil;

React/Views/RCTNavigator.m

@@ -200,8 +200,8 @@ NSInteger kNeverProgressed = -10000;
 
 // Previous views are only mainted in order to detect incorrect
 // addition/removal of views below the `requestedTopOfStack`
-@property (nonatomic, copy, readwrite) NSArray *previousViews;
-@property (nonatomic, readwrite, strong) NSMutableArray *currentViews;
+@property (nonatomic, copy, readwrite) NSArray<RCTNavItem *> *previousViews;
+@property (nonatomic, readwrite, strong) NSMutableArray<RCTNavItem *> *currentViews;
 @property (nonatomic, readwrite, strong) RCTNavigationController *navigationController;
 /**
  * Display link is used to get high frequency sample rate during
@@ -400,7 +400,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
  * `requestedTopOfStack` changes, there had better be enough subviews present
  * to satisfy the push/pop.
  */
-- (void)insertReactSubview:(UIView *)view atIndex:(NSInteger)atIndex
+- (void)insertReactSubview:(RCTNavItem *)view atIndex:(NSInteger)atIndex
 {
   RCTAssert([view isKindOfClass:[RCTNavItem class]], @"RCTNavigator only accepts RCTNavItem subviews");
   RCTAssert(
@@ -410,7 +410,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   [_currentViews insertObject:view atIndex:atIndex];
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<RCTNavItem *> *)reactSubviews
 {
   return _currentViews;
 }
@@ -422,7 +422,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   _navigationController.view.frame = self.bounds;
 }
 
-- (void)removeReactSubview:(UIView *)subview
+- (void)removeReactSubview:(RCTNavItem *)subview
 {
   if (_currentViews.count <= 0 || subview == _currentViews[0]) {
     RCTLogError(@"Attempting to remove invalid RCT subview of RCTNavigator");

React/Views/RCTPicker.h

@@ -9,6 +9,12 @@
 
 #import <UIKit/UIKit.h>
 
+#import "UIView+React.h"
+
 @interface RCTPicker : UIPickerView
 
+@property (nonatomic, copy) NSArray<NSDictionary *> *items;
+@property (nonatomic, assign) NSInteger selectedIndex;
+@property (nonatomic, copy) RCTBubblingEventBlock onChange;
+
 @end

React/Views/RCTPicker.m

@@ -10,14 +10,8 @@
 #import "RCTPicker.h"
 
 #import "RCTUtils.h"
-#import "UIView+React.h"
 
 @interface RCTPicker() <UIPickerViewDataSource, UIPickerViewDelegate>
-
-@property (nonatomic, copy) NSArray *items;
-@property (nonatomic, assign) NSInteger selectedIndex;
-@property (nonatomic, copy) RCTBubblingEventBlock onChange;
-
 @end
 
 @implementation RCTPicker
@@ -33,7 +27,7 @@
 
 RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
 
-- (void)setItems:(NSArray *)items
+- (void)setItems:(NSArray<NSDictionary *> *)items
 {
   _items = [items copy];
   [self setNeedsLayout];

React/Views/RCTScrollView.m

@@ -117,7 +117,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 - (RCTScrollEvent *)coalesceWithEvent:(RCTScrollEvent *)newEvent
 {
-  NSArray *updatedChildFrames = [_userData[@"updatedChildFrames"] arrayByAddingObjectsFromArray:newEvent->_userData[@"updatedChildFrames"]];
+  NSArray<NSDictionary *> *updatedChildFrames = [_userData[@"updatedChildFrames"] arrayByAddingObjectsFromArray:newEvent->_userData[@"updatedChildFrames"]];
 
   if (updatedChildFrames) {
     NSMutableDictionary *userData = [newEvent->_userData mutableCopy];
@@ -360,7 +360,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   RCTCustomScrollView *_scrollView;
   UIView *_contentView;
   NSTimeInterval _lastScrollDispatchTime;
-  NSMutableArray *_cachedChildFrames;
+  NSMutableArray<NSValue *> *_cachedChildFrames;
   BOOL _allowNextScrollNoMatterWhat;
   CGRect _lastClippedToRect;
 }
@@ -412,7 +412,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   [subview removeFromSuperview];
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<UIView<RCTComponent> *> *)reactSubviews
 {
   return _contentView ? @[_contentView] : @[];
 }
@@ -564,7 +564,7 @@ RCT_SCROLL_EVENT_HANDLER(scrollViewDidZoom, RCTScrollEventTypeMove)
       (_scrollEventThrottle > 0 && _scrollEventThrottle < (now - _lastScrollDispatchTime))) {
 
     // Calculate changed frames
-    NSArray *childFrames = [self calculateChildFramesData];
+    NSArray<NSDictionary *> *childFrames = [self calculateChildFramesData];
 
     // Dispatch event
     [_eventDispatcher sendScrollEventWithType:RCTScrollEventTypeMove
@@ -579,9 +579,9 @@ RCT_SCROLL_EVENT_HANDLER(scrollViewDidZoom, RCTScrollEventTypeMove)
   RCT_FORWARD_SCROLL_EVENT(scrollViewDidScroll:scrollView);
 }
 
-- (NSArray *)calculateChildFramesData
+- (NSArray<NSDictionary *> *)calculateChildFramesData
 {
-    NSMutableArray *updatedChildFrames = [NSMutableArray new];
+    NSMutableArray<NSDictionary *> *updatedChildFrames = [NSMutableArray new];
     [[_contentView reactSubviews] enumerateObjectsUsingBlock:
      ^(UIView *subview, NSUInteger idx, __unused BOOL *stop) {
 

React/Views/RCTScrollViewManager.m

@@ -16,7 +16,7 @@
 
 @interface RCTScrollView (Private)
 
-- (NSArray *)calculateChildFramesData;
+- (NSArray<NSDictionary *> *)calculateChildFramesData;
 
 @end
 
@@ -83,13 +83,13 @@ RCT_EXPORT_METHOD(getContentSize:(nonnull NSNumber *)reactTag
 {
   [self.bridge.uiManager addUIBlock:^(__unused RCTUIManager *uiManager, RCTSparseArray *viewRegistry) {
 
-    UIView *view = viewRegistry[reactTag];
-    if (!view) {
-      RCTLogError(@"Cannot find view with tag #%@", reactTag);
+    RCTScrollView *view = viewRegistry[reactTag];
+    if (!view || ![view isKindOfClass:[RCTScrollView class]]) {
+      RCTLogError(@"Cannot find RCTScrollView with tag #%@", reactTag);
       return;
     }
 
-    CGSize size = ((RCTScrollView *)view).scrollView.contentSize;
+    CGSize size = view.scrollView.contentSize;
     callback(@[@{
       @"width" : @(size.width),
       @"height" : @(size.height)
@@ -102,20 +102,20 @@ RCT_EXPORT_METHOD(calculateChildFrames:(nonnull NSNumber *)reactTag
 {
   [self.bridge.uiManager addUIBlock:^(__unused RCTUIManager *uiManager, RCTSparseArray *viewRegistry) {
 
-    UIView *view = viewRegistry[reactTag];
-    if (!view) {
-      RCTLogError(@"Cannot find view with tag #%@", reactTag);
+    RCTScrollView *view = viewRegistry[reactTag];
+    if (!view || ![view isKindOfClass:[RCTScrollView class]]) {
+      RCTLogError(@"Cannot find RCTScrollView with tag #%@", reactTag);
       return;
     }
 
-    NSArray *childFrames = [((RCTScrollView *)view) calculateChildFramesData];
+    NSArray<NSDictionary *> *childFrames = [view calculateChildFramesData];
     if (childFrames) {
       callback(@[childFrames]);
     }
   }];
 }
 
-- (NSArray *)customDirectEventTypes
+- (NSArray<NSString *> *)customDirectEventTypes
 {
   return @[
     @"scrollBeginDrag",

React/Views/RCTSegmentedControl.h

@@ -13,7 +13,7 @@
 
 @interface RCTSegmentedControl : UISegmentedControl
 
-@property (nonatomic, copy) NSArray *values;
+@property (nonatomic, copy) NSArray<NSString *> *values;
 @property (nonatomic, assign) NSInteger selectedIndex;
 @property (nonatomic, copy) RCTBubblingEventBlock onChange;
 

React/Views/RCTSegmentedControl.m

@@ -25,7 +25,7 @@
   return self;
 }
 
-- (void)setValues:(NSArray *)values
+- (void)setValues:(NSArray<NSString *> *)values
 {
   _values = [values copy];
   [self removeAllSegments];

React/Views/RCTShadowView.h

@@ -35,6 +35,9 @@ typedef void (^RCTApplierBlock)(RCTSparseArray *viewRegistry);
  */
 @interface RCTShadowView : NSObject <RCTComponent>
 
+- (NSArray<RCTShadowView *> *)reactSubviews;
+- (RCTShadowView *)reactSuperview;
+
 @property (nonatomic, weak, readonly) RCTShadowView *superview;
 @property (nonatomic, assign, readonly) css_node_t *cssNode;
 @property (nonatomic, copy) NSString *viewName;
@@ -120,27 +123,27 @@ typedef void (^RCTApplierBlock)(RCTSparseArray *viewRegistry);
  * The applierBlocks set contains RCTApplierBlock functions that must be applied
  * on the main thread in order to update the view.
  */
-- (void)collectUpdatedProperties:(NSMutableSet *)applierBlocks
+- (void)collectUpdatedProperties:(NSMutableSet<RCTApplierBlock> *)applierBlocks
                 parentProperties:(NSDictionary *)parentProperties;
 
 /**
  * Process the updated properties and apply them to view. Shadow view classes
  * that add additional propagating properties should override this method.
  */
-- (NSDictionary *)processUpdatedProperties:(NSMutableSet *)applierBlocks
+- (NSDictionary *)processUpdatedProperties:(NSMutableSet<RCTApplierBlock> *)applierBlocks
                           parentProperties:(NSDictionary *)parentProperties NS_REQUIRES_SUPER;
 
 /**
  * Calculate all views whose frame needs updating after layout has been calculated.
  * The viewsWithNewFrame set contains the reactTags of the views that need updating.
  */
-- (void)collectRootUpdatedFrames:(NSMutableSet *)viewsWithNewFrame;
+- (void)collectRootUpdatedFrames:(NSMutableSet<RCTShadowView *> *)viewsWithNewFrame;
 
 /**
  * Recursively apply layout to children.
  */
 - (void)applyLayoutNode:(css_node_t *)node
-      viewsWithNewFrame:(NSMutableSet *)viewsWithNewFrame
+      viewsWithNewFrame:(NSMutableSet<RCTShadowView *> *)viewsWithNewFrame
        absolutePosition:(CGPoint)absolutePosition NS_REQUIRES_SUPER;
 
 /**

React/Views/RCTShadowView.m

@@ -36,7 +36,7 @@ typedef NS_ENUM(unsigned int, meta_prop_t) {
   RCTUpdateLifecycle _propagationLifecycle;
   RCTUpdateLifecycle _textLifecycle;
   NSDictionary *_lastParentProperties;
-  NSMutableArray *_reactSubviews;
+  NSMutableArray<RCTShadowView *> *_reactSubviews;
   BOOL _recomputePadding;
   BOOL _recomputeMargin;
   BOOL _recomputeBorder;
@@ -123,7 +123,7 @@ static void RCTProcessMetaProps(const float metaProps[META_PROP_COUNT], float st
 // You'll notice that this is the same width we calculated for the parent view because we've taken its position into account.
 
 - (void)applyLayoutNode:(css_node_t *)node
-      viewsWithNewFrame:(NSMutableSet *)viewsWithNewFrame
+      viewsWithNewFrame:(NSMutableSet<RCTShadowView *> *)viewsWithNewFrame
        absolutePosition:(CGPoint)absolutePosition
 {
   if (!node->layout.should_update) {
@@ -171,7 +171,7 @@ static void RCTProcessMetaProps(const float metaProps[META_PROP_COUNT], float st
   }
 }
 
-- (NSDictionary *)processUpdatedProperties:(NSMutableSet *)applierBlocks
+- (NSDictionary *)processUpdatedProperties:(NSMutableSet<RCTApplierBlock> *)applierBlocks
                           parentProperties:(NSDictionary *)parentProperties
 {
   // TODO: we always refresh all propagated properties when propagation is
@@ -201,7 +201,7 @@ static void RCTProcessMetaProps(const float metaProps[META_PROP_COUNT], float st
   return parentProperties;
 }
 
-- (void)collectUpdatedProperties:(NSMutableSet *)applierBlocks
+- (void)collectUpdatedProperties:(NSMutableSet<RCTApplierBlock> *)applierBlocks
                 parentProperties:(NSDictionary *)parentProperties
 {
   if (_propagationLifecycle == RCTUpdateLifecycleComputed && [parentProperties isEqualToDictionary:_lastParentProperties]) {
@@ -234,7 +234,7 @@ static void RCTProcessMetaProps(const float metaProps[META_PROP_COUNT], float st
   }
 }
 
-- (void)collectRootUpdatedFrames:(NSMutableSet *)viewsWithNewFrame
+- (void)collectRootUpdatedFrames:(NSMutableSet<RCTShadowView *> *)viewsWithNewFrame
 {
   RCTAssert(RCTIsReactRootView(self.reactTag),
             @"The method has been called on a view with react tag %@, which is not a root view", self.reactTag);
@@ -367,7 +367,7 @@ static void RCTProcessMetaProps(const float metaProps[META_PROP_COUNT], float st
   _cssNode->children_count = (int)_reactSubviews.count;
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<RCTShadowView *> *)reactSubviews
 {
   return _reactSubviews;
 }

React/Views/RCTTabBar.m

@@ -26,7 +26,7 @@
 {
   BOOL _tabsChanged;
   UITabBarController *_tabController;
-  NSMutableArray *_tabViews;
+  NSMutableArray<RCTTabBarItem *> *_tabViews;
 }
 
 - (instancetype)initWithFrame:(CGRect)frame
@@ -52,12 +52,12 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   _tabController.delegate = nil;
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<RCTTabBarItem *> *)reactSubviews
 {
   return _tabViews;
 }
 
-- (void)insertReactSubview:(UIView *)view atIndex:(NSInteger)atIndex
+- (void)insertReactSubview:(RCTTabBarItem *)view atIndex:(NSInteger)atIndex
 {
   if (![view isKindOfClass:[RCTTabBarItem class]]) {
     RCTLogError(@"subview should be of type RCTTabBarItem");
@@ -67,7 +67,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   _tabsChanged = YES;
 }
 
-- (void)removeReactSubview:(UIView *)subview
+- (void)removeReactSubview:(RCTTabBarItem *)subview
 {
   if (_tabViews.count == 0) {
     RCTLogError(@"should have at least one view to remove a subview");
@@ -92,7 +92,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
 
   if (_tabsChanged) {
 
-    NSMutableArray *viewControllers = [NSMutableArray array];
+    NSMutableArray<UIViewController *> *viewControllers = [NSMutableArray array];
     for (RCTTabBarItem *tab in [self reactSubviews]) {
       UIViewController *controller = tab.reactViewController;
       if (!controller) {
@@ -105,7 +105,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
     _tabsChanged = NO;
   }
 
-  [[self reactSubviews] enumerateObjectsUsingBlock:
+  [_tabViews enumerateObjectsUsingBlock:
    ^(RCTTabBarItem *tab, NSUInteger index, __unused BOOL *stop) {
     UIViewController *controller = _tabController.viewControllers[index];
     controller.tabBarItem = tab.barItem;
@@ -148,7 +148,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
 - (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
 {
   NSUInteger index = [tabBarController.viewControllers indexOfObject:viewController];
-  RCTTabBarItem *tab = [self reactSubviews][index];
+  RCTTabBarItem *tab = _tabViews[index];
   if (tab.onPress) tab.onPress(nil);
   return NO;
 }

React/Views/RCTView.m

@@ -92,7 +92,7 @@ static NSString *RCTRecursiveAccessibilityLabel(UIView *view)
 
 @implementation RCTView
 {
-  NSMutableArray *_reactSubviews;
+  NSMutableArray<UIView<RCTComponent> *> *_reactSubviews;
   UIColor *_backgroundColor;
 }
 
@@ -413,7 +413,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:unused)
   [subview removeFromSuperview];
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<UIView<RCTComponent> *> *)reactSubviews
 {
   // The _reactSubviews array is only used when we have hidden
   // offscreen views. If _reactSubviews is nil, we can assume

React/Views/RCTViewManager.h

@@ -70,7 +70,7 @@ typedef void (^RCTViewManagerUIBlock)(RCTUIManager *uiManager, RCTSparseArray *v
  * Note that this method is not inherited when you subclass a view module, and
  * you should not call [super customBubblingEventTypes] when overriding it.
  */
-- (NSArray *)customBubblingEventTypes;
+- (NSArray<NSString *> *)customBubblingEventTypes;
 
 /**
  * DEPRECATED: declare properties of type RCTDirectEventBlock instead
@@ -83,7 +83,7 @@ typedef void (^RCTViewManagerUIBlock)(RCTUIManager *uiManager, RCTSparseArray *v
  * Note that this method is not inherited when you subclass a view module, and
  * you should not call [super customDirectEventTypes] when overriding it.
  */
-- (NSArray *)customDirectEventTypes;
+- (NSArray<NSString *> *)customDirectEventTypes;
 
 /**
  * Called to notify manager that layout has finished, in case any calculated
@@ -103,13 +103,13 @@ typedef void (^RCTViewManagerUIBlock)(RCTUIManager *uiManager, RCTSparseArray *v
  * This handles the simple case, where JS and native property names match.
  */
 #define RCT_EXPORT_VIEW_PROPERTY(name, type) \
-+ (NSArray *)propConfig_##name { return @[@#type]; }
++ (NSArray<NSString *> *)propConfig_##name { return @[@#type]; }
 
 /**
  * This macro maps a named property to an arbitrary key path in the view.
  */
 #define RCT_REMAP_VIEW_PROPERTY(name, keyPath, type) \
-+ (NSArray *)propConfig_##name { return @[@#type, @#keyPath]; }
++ (NSArray<NSString *> *)propConfig_##name { return @[@#type, @#keyPath]; }
 
 /**
  * This macro can be used when you need to provide custom logic for setting
@@ -124,6 +124,6 @@ RCT_REMAP_VIEW_PROPERTY(name, __custom__, type)         \
  * This macro is used to map properties to the shadow view, instead of the view.
  */
 #define RCT_EXPORT_SHADOW_PROPERTY(name, type) \
-+ (NSArray *)propConfigShadow_##name { return @[@#type]; }
++ (NSArray<NSString *> *)propConfigShadow_##name { return @[@#type]; }
 
 @end

React/Views/RCTViewManager.m

@@ -69,7 +69,7 @@ RCT_EXPORT_MODULE()
   return [RCTShadowView new];
 }
 
-- (NSArray *)customBubblingEventTypes
+- (NSArray<NSString *> *)customBubblingEventTypes
 {
   return @[
 
@@ -90,7 +90,7 @@ RCT_EXPORT_MODULE()
   ];
 }
 
-- (NSArray *)customDirectEventTypes
+- (NSArray<NSString *> *)customDirectEventTypes
 {
   return @[];
 }

React/Views/UIView+React.h

@@ -15,6 +15,9 @@
 
 @interface UIView (React) <RCTComponent>
 
+- (NSArray<UIView<RCTComponent> *> *)reactSubviews;
+- (UIView<RCTComponent> *)reactSuperview;
+
 /**
  * Used by the UIIManager to set the view frame.
  * May be overriden to disable animation, etc.

React/Views/UIView+React.m

@@ -51,12 +51,12 @@
   [subview removeFromSuperview];
 }
 
-- (NSArray *)reactSubviews
+- (NSArray<UIView<RCTComponent> *> *)reactSubviews
 {
   return self.subviews;
 }
 
-- (UIView *)reactSuperview
+- (UIView<RCTComponent> *)reactSuperview
 {
   return self.superview;
 }