Added setStackRoot top level api

lib/ios/RNNBridgeModule.m

 	}];
 }
 
+RCT_EXPORT_METHOD(setStackRoot:(NSString*)componentId layout:(NSDictionary*)layout resolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject) {
+	[_commandsHandler setStackRoot:componentId layout:layout completion:^{
+		resolve(componentId);
+	}];
+}
+
 RCT_EXPORT_METHOD(popTo:(NSString*)componentId resolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject) {
 	[_commandsHandler popTo:componentId completion:^{
 		resolve(componentId);

lib/ios/RNNCommandsHandler.h

 
 -(void) popToRoot:(NSString*)componentId completion:(RNNTransitionCompletionBlock)completion;
 
+-(void)setStackRoot:(NSString*)componentId layout:(NSDictionary*)layout completion:(RNNTransitionCompletionBlock)completion;
+
 -(void) showModal:(NSDictionary*)layout completion:(RNNTransitionCompletionBlock)completion;
 
 -(void) dismissModal:(NSString*)componentId completion:(RNNTransitionCompletionBlock)completion;

lib/ios/RNNCommandsHandler.m

 	[_controllerFactory setDefaultOptionsDict:optionsDict];
 }
 
--(void) push:(NSString*)componentId layout:(NSDictionary*)layout completion:(RNNTransitionCompletionBlock)completion {
+-(void)push:(NSString*)componentId layout:(NSDictionary*)layout completion:(RNNTransitionCompletionBlock)completion {
 	[self assertReady];
 	
 	UIViewController<RNNRootViewProtocol> *newVc = [_controllerFactory createLayoutAndSaveToStore:layout];
 	}];
 }
 
+-(void)setStackRoot:(NSString*)componentId layout:(NSDictionary*)layout completion:(RNNTransitionCompletionBlock)completion {
+	[self assertReady];
+	
+	UIViewController<RNNRootViewProtocol> *newVc = [_controllerFactory createLayoutAndSaveToStore:layout];
+	[_navigationStackManager setRoot:newVc fromComponent:componentId completion:^{
+		completion();
+	}];
+}
+
 -(void)pop:(NSString*)componentId options:(NSDictionary*)options completion:(RNNTransitionCompletionBlock)completion {
 	[self assertReady];
 	[CATransaction begin];

lib/ios/RNNNavigationStackManager.h

 -(void)pop:(NSString*)componentId withTransitionOptions:(RNNAnimationOptions*)transitionOptions;
 -(void)popTo:(NSString*)componentId;
 -(void)popToRoot:(NSString*)componentId;
+-(void)setRoot:(UIViewController<RNNRootViewProtocol> *)newRoot fromComponent:(NSString *)componentId completion:(RNNTransitionCompletionBlock)completion;
 
 @end

lib/ios/RNNNavigationStackManager.m

 	}
 }
 
--(void) popToRoot:(NSString*)componentId {
+-(void)popToRoot:(NSString*)componentId {
 	UIViewController* vc = [_store findComponentForId:componentId];
 	UINavigationController* nvc = [vc navigationController];
 	NSArray* poppedVCs = [nvc popToRootViewControllerAnimated:YES];
 	[self removePopedViewControllers:poppedVCs];
 }
 
+-(void)setRoot:(UIViewController<RNNRootViewProtocol> *)newRoot fromComponent:(NSString *)componentId completion:(RNNTransitionCompletionBlock)completion {
+	UIViewController* vc = [_store findComponentForId:componentId];
+	UINavigationController* nvc = [vc navigationController];
+	[CATransaction begin];
+	[CATransaction setCompletionBlock:^{
+		if (completion) {
+			completion();
+		}
+	}];
+	
+	[nvc setViewControllers:@[newRoot] animated:newRoot.options.animated];
+	
+	[CATransaction commit];
+}
+
 -(void)removePopedViewControllers:(NSArray*)viewControllers {
 	for (UIViewController *popedVC in viewControllers) {
 		[_store removeComponentByViewControllerInstance:popedVC];

lib/src/Navigation.ts

     return this.commands.popToRoot(componentId);
   }
 
+  /**
+   * Sets new root component to stack.
+   */
+  public setStackRoot(componentId: string, layout): Promise<any> {
+    return this.commands.setStackRoot(componentId, layout);
+  }
+
   /**
    * Show overlay on top of the entire app
    */

lib/src/adapters/NativeCommandsSender.ts

     return this.nativeCommandsModule.popToRoot(componentId);
   }
 
+  setStackRoot(onComponentId: string, layout: object) {
+    return this.nativeCommandsModule.setStackRoot(onComponentId, layout);
+  }
+
   showModal(layout: object) {
     return this.nativeCommandsModule.showModal(layout);
   }

lib/src/commands/Commands.test.ts

     });
   });
 
+  describe('setStackRoot', () => {
+    it('parses into correct layout node and sends to native', () => {
+      uut.setStackRoot('theComponentId', { component: { name: 'com.example.MyScreen' } });
+      expect(mockCommandsSender.setStackRoot).toHaveBeenCalledTimes(1);
+      expect(mockCommandsSender.setStackRoot).toHaveBeenCalledWith('theComponentId', {
+        type: 'Component',
+        id: 'Component+UNIQUE_ID',
+        data: {
+          name: 'com.example.MyScreen',
+          options: {}
+        },
+        children: []
+      });
+    });
+  });
+
   describe('showOverlay', () => {
     it('sends command to native after parsing into a correct layout tree', () => {
       uut.showOverlay({
         pop: ['id', {}],
         popTo: ['id'],
         popToRoot: ['id'],
+        setStackRoot: ['id', {}],
         showOverlay: [{}],
         dismissOverlay: ['id'],
       };
         pop: { componentId: 'id', options: {} },
         popTo: { componentId: 'id' },
         popToRoot: { componentId: 'id' },
+        setStackRoot: { componentId: 'id', layout: 'parsed' },
         showOverlay: { layout: 'parsed' },
         dismissOverlay: { componentId: 'id' },
       };

lib/src/commands/Commands.ts

     return result;
   }
 
+  public setStackRoot(componentId, simpleApi) {
+    const input = _.cloneDeep(simpleApi);
+
+    const layout = this.layoutTreeParser.parse(input);
+    this.layoutTreeCrawler.crawl(layout);
+
+    const result = this.nativeCommandsSender.setStackRoot(componentId, layout);
+    this.commandsObserver.notify('setStackRoot', { componentId, layout });
+    return result;
+  }
+
   public showOverlay(simpleApi) {
     const input = _.cloneDeep(simpleApi);
 

playground/src/screens/PushedScreen.js

     this.onClickPopPrevious = this.onClickPopPrevious.bind(this);
     this.onClickPopToFirstPosition = this.onClickPopToFirstPosition.bind(this);
     this.onClickPopToRoot = this.onClickPopToRoot.bind(this);
+    this.onClickSetStackRoot = this.onClickSetStackRoot.bind(this);
   }
 
   render() {
         <Button title='Pop' testID={testIDs.POP_BUTTON} onPress={this.onClickPop} />
         <Button title='Pop Previous' testID={testIDs.POP_PREVIOUS_BUTTON} onPress={this.onClickPopPrevious} />
         <Button title='Pop To Root' testID={testIDs.POP_TO_ROOT} onPress={this.onClickPopToRoot} />
+        <Button title='Set Stack Root' testID={testIDs.SET_STACK_ROOT_BUTTON} onPress={this.onClickSetStackRoot} />
         {stackPosition > 2 && <Button title='Pop To Stack Position 1' testID={testIDs.POP_STACK_POSITION_ONE_BUTTON} onPress={this.onClickPopToFirstPosition} />}
         <Text style={styles.footer}>{`this.props.componentId = ${this.props.componentId}`}</Text>
       </View>
     await Navigation.popToRoot(this.props.componentId);
   }
 
+  async onClickSetStackRoot() {
+    await Navigation.setStackRoot(this.props.componentId, {
+      component: {
+        name: 'navigation.playground.PushedScreen',
+        passProps: {
+          stackPosition: this.getStackPosition() + 1,
+          previousScreenIds: _.concat([], this.props.previousScreenIds || [], this.props.componentId)
+        },
+        options: {
+          topBar: {
+            title: {
+              text: `Pushed ${this.getStackPosition() + 1}`
+            }
+          }
+        }
+      }
+    });
+  }
+
   getStackPosition() {
     return this.props.stackPosition || 1;
   }

playground/src/testIDs.js

   COMPLEX_LAYOUT_BUTTON: `COMPLEX_LAYOUT_BUTTON`,
   EXTERNAL_COMPONENT_IN_STACK: `EXTERNAL_COMPONENT_IN_STACK`,
   EXTERNAL_COMPONENT_IN_DEEP_STACK: `EXTERNAL_COMPONENT_IN_DEEP_STACK`,
+  SET_STACK_ROOT_BUTTON: `SET_STACK_ROOT_BUTTON`,
 
   // Elements
   SCROLLVIEW_ELEMENT: `SCROLLVIEW_ELEMENT`,