closes #2720

lib/ios/RNNBottomTabsOptions.h

 @property (nonatomic, strong) NSNumber* animateHide;
 @property (nonatomic, strong) NSNumber* currentTabIndex;
 @property (nonatomic, strong) NSString* testID;
-@property (nonatomic, strong) NSNumber* drawUnder;
+@property (nonatomic, strong) NSNumber* drawBehind;
 @property (nonatomic, strong) NSString* currentTabId;
 
 @property (nonatomic, strong) NSNumber* translucent;

lib/ios/RNNBottomTabsOptions.m

 		viewController.tabBarController.tabBar.accessibilityIdentifier = self.testID;
 	}
 	
-	if (self.drawUnder) {
-		if ([self.drawUnder boolValue]) {
+	if (self.drawBehind) {
+		if ([self.drawBehind boolValue]) {
 			viewController.edgesForExtendedLayout |= UIRectEdgeBottom;
 		} else {
 			viewController.edgesForExtendedLayout &= ~UIRectEdgeBottom;

lib/ios/RNNNavigationButtons.m

 	barButtonItem.target = self;
 	barButtonItem.action = @selector(onButtonPress:);
 	
-	NSNumber *disabled = dictionary[@"disabled"];
-	BOOL disabledBool = disabled ? [disabled boolValue] : NO;
-	if (disabledBool) {
-		[barButtonItem setEnabled:NO];
-	}
+	NSNumber *enabled = dictionary[@"enabled"];
+	BOOL enabledBool = enabled ? [enabled boolValue] : YES;
+	[barButtonItem setEnabled:enabledBool];
 	
 	NSNumber *disableIconTintString = dictionary[@"disableIconTint"];
 	BOOL disableIconTint = disableIconTintString ? [disableIconTintString boolValue] : NO;

lib/ios/RNNOptions.m

 
 -(void)mergeWith:(NSDictionary *)otherOptions {
 	for (id key in otherOptions) {
-		[self setValue:[otherOptions objectForKey:key] forKey:key];
+		if ([self hasProperty:key]) {
+			[self setValue:[otherOptions objectForKey:key] forKey:key];
+		}
 	}
 }
 
+-(BOOL)hasProperty:(NSString*)propName {
+	return [self respondsToSelector:NSSelectorFromString(propName)];
+}
+
 @end

lib/ios/RNNTopBarOptions.h

 @property (nonatomic, strong) NSNumber* buttonColor;
 @property (nonatomic, strong) NSNumber* translucent;
 @property (nonatomic, strong) NSNumber* transparent;
-@property (nonatomic, strong) NSNumber* drawUnder;
+@property (nonatomic, strong) NSNumber* drawBehind;
 @property (nonatomic, strong) NSNumber* textFontSize;
 @property (nonatomic, strong) NSNumber* noBorder;
 @property (nonatomic, strong) NSNumber* blur;

lib/ios/RNNTopBarOptions.m

 		viewController.navigationController.navigationBar.translucent = [self.translucent boolValue];
 	}
 	
-	if (self.drawUnder) {
-		if ([self.drawUnder boolValue]) {
+	if (self.drawBehind) {
+		if ([self.drawBehind boolValue]) {
 			viewController.edgesForExtendedLayout |= UIRectEdgeTop;
 		} else {
 			viewController.edgesForExtendedLayout &= ~UIRectEdgeTop;

lib/ios/ReactNativeNavigationTests/RNNNavigationOptionsTest.m

     [super setUp];
 }
 
--(void)testInitCreatesInstanceType{
+- (void)testInitCreatesInstanceType {
 	RNNNavigationOptions* options = [[RNNNavigationOptions alloc] initWithDict:@{}];
 	XCTAssertTrue([options isKindOfClass:[RNNNavigationOptions class]]);
 }
--(void)testAddsStyleFromDictionaryWithInit{
+- (void)testAddsStyleFromDictionaryWithInit {
 	RNNNavigationOptions* options = [[RNNNavigationOptions alloc] initWithDict:@{@"topBar": @{@"backgroundColor" : @(0xff0000ff)}}];
 	XCTAssertTrue(options.topBar.backgroundColor);
 }
--(void)testThrowsWhenStyleDoesNotExist{
-	XCTAssertThrows([[RNNNavigationOptions alloc] initWithDict:@{@"topBar": @{@"someColor" : @(0xff0000ff)}}]);
-}
 
--(void)testChangeRNNNavigationOptionsDynamically{
+- (void)testChangeRNNNavigationOptionsDynamically {
 	RNNNavigationOptions* options = [[RNNNavigationOptions alloc] initWithDict:@{@"topBar": @{@"backgroundColor" : @(0xff0000ff)}}];
 	NSDictionary* dynamicOptions = @{@"topBar": @{@"textColor" : @(0xffff00ff), @"title" : @"hello"}};
 	[options mergeWith:dynamicOptions];
 	XCTAssertTrue([options.topBar.title isEqual:@"hello"]);
 }
 
--(void)testChangeRNNNavigationOptionsWithInvalidProperties{
+- (void)testChangeRNNNavigationOptionsWithInvalidProperties {
 	RNNNavigationOptions* options = [[RNNNavigationOptions alloc] initWithDict:@{@"topBar": @{@"backgroundColor" : @(0xff0000ff)}}];
 	NSDictionary* dynamicOptions = @{@"topBar": @{@"titleeeee" : @"hello"}};
-	XCTAssertThrows([options mergeWith:dynamicOptions]);
+	XCTAssertNoThrow([options mergeWith:dynamicOptions]);
 }
 
 @end

lib/ios/ReactNativeNavigationTests/RNNRootViewControllerTest.m

 -(void)testRightButtonsWithTitle_withStyle {
 	NSNumber* inputColor = @(0xFFFF0000);
 	
-	self.options.topBar.rightButtons = @[@{@"id": @"testId", @"title": @"test", @"disabled": @true, @"buttonColor": inputColor, @"buttonFontSize": @22, @"buttonFontWeight": @"800"}];
+	self.options.topBar.rightButtons = @[@{@"id": @"testId", @"title": @"test", @"enabled": @false, @"buttonColor": inputColor, @"buttonFontSize": @22, @"buttonFontWeight": @"800"}];
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	
 -(void)testLeftButtonsWithTitle_withStyle {
 	NSNumber* inputColor = @(0xFFFF0000);
 	
-	self.options.topBar.leftButtons = @[@{@"id": @"testId", @"title": @"test", @"disabled": @true, @"buttonColor": inputColor, @"buttonFontSize": @22, @"buttonFontWeight": @"800"}];
+	self.options.topBar.leftButtons = @[@{@"id": @"testId", @"title": @"test", @"enabled": @false, @"buttonColor": inputColor, @"buttonFontSize": @22, @"buttonFontWeight": @"800"}];
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	
 }
 
 -(void)testTopBarDrawUnder_true {
-	self.options.topBar.drawUnder = @(1);
+	self.options.topBar.drawBehind = @(1);
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	
 }
 
 -(void)testTopBarDrawUnder_false {
-	self.options.topBar.drawUnder = @(0);
+	self.options.topBar.drawBehind = @(0);
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	
 }
 
 -(void)testBottomTabsDrawUnder_true {
-	self.options.bottomTabs.drawUnder = @(1);
+	self.options.bottomTabs.drawBehind = @(1);
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	
 }
 
 -(void)testBottomTabsDrawUnder_false {
-	self.options.bottomTabs.drawUnder = @(0);
+	self.options.bottomTabs.drawBehind = @(0);
 	__unused UINavigationController* nav = [[UINavigationController alloc] initWithRootViewController:self.uut];
 	[self.uut viewWillAppear:false];
 	

playground/src/screens/ScrollViewScreen.js

     return {
       topBar: {
         title: 'Collapse',
-        ...Platform.select({
-          android: {
-            drawBehind: true
-          }
-        }),
+        drawBehind: true,
         textColor: 'black',
         textFontSize: 16
       }