React Native: How to export a method with a return value?

Question

What is the best way to export a method with a return value in React Native?

I know there is RCT_EXPORT_METHOD, but that only works for methods that are (void) and therefore don't return anything. Preferably I don't need to export the whole class, just a few methods.

The other option would be to have a callback, but I would like to avoid that if possible as it bloats up the code too much in my use case. Are there are any other options I might have missed?

Answer 1

You can also now use promises, which tend to look a little nicer in your JS.

Objective C:

RCT_REMAP_METHOD(getThing, resolver: (RCTPromiseResolveBlock)resolve      rejecter:(RCTPromiseRejectBlock)reject) {   if( condition ) {     NSString *thingToReturn = @"ALL OK";     resolve(thingToReturn);   } else {     reject([NSError errorWithDomain:@"com.companyname.app" code:0 userInfo:@{ @"text": @"something happend" }]);   } } 

Then in JS:

async onPress() {   try {     const status = await CustomModule.getThing();     // do something with status   } catch(e) {     console.error(e);   } }