Works only when a React-Native view is displayed (iOS)

[plbrault]

I am trying to run a JavaScript function from native code on iOS. It works properly when the current view is a React Native view, but it does not work when the current view is a native one. Is there any way to make it work?

I am using the package version from master, with version 0.39 of React Native.

[artemyarulin]

Hm, that's weird, I've been using react-native-eval exactly like that - having native view on a top. Let me check

[artemyarulin]

Yep, was able to reproduce, will check it during weekend, thanks

[artemyarulin]

Figured it out. The problem is that you need to save RCTRootView somewhere, otherwise garbage collector will reset it and RN wouldn't be initialized. Here example AppDelegate code:

#import "AppDelegate.h"
#import "RCTBundleURLProvider.h"
#import "RCTRootView.h"
#import "RNMEvaluator.h"

@implementation AppDelegate
{
  RCTRootView* rootView; // Save it as an instance variable for example
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  NSURL *jsCodeLocation;

  jsCodeLocation = [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"index.ios" fallbackResource:nil];

  rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                      moduleName:@"app"
                                               initialProperties:nil
                                                   launchOptions:launchOptions];
  
  // now as we saved rootView we can start calling RNMEvaluator
  [RNMEvaluator callSyncFunction:rootView.bridge
                            name:@"Math.pow"
                            args:@[@2,@2]
                              cb:^(NSString *error, id returnValue) {
                                if (error)
                                  NSLog(@"Error occured: %@", error);
                                else
                                  NSLog(@"Function returned: %@", returnValue);
                              }];
    
  rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];
  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  UIViewController *rootViewController = [UIViewController new];
  // Or you will get the same if you assing it as a view to some view controller
  //rootViewController.view = rootView;
  self.window.rootViewController = rootViewController;
  [self.window makeKeyAndVisible];
  return YES;
}
@end

I will fix README documentation and mention this issue there. Thank you!

[plbrault]

Thank you very much. Looking forward to try this on Monday!

[plbrault]

It works indeed, thank you!