Access data stored in AsyncStorage from ios native code (objective c)

Question

I need to access data stored in AsyncStorage from iOS native Objective C code.

This is needed to get the data in sync instead of sending App event to JS and then send it back to native code.

Answer 1

I've just been faced with the same problem.

My solution was to move the code native side.

On iOS:

#import <React/RCTAsyncLocalStorage.h>
#import <React/RCTBridgeModule.h>

RCTResponseSenderBlock completion = ^(NSArray *response) {
  NSString *theme = response[1][0][0][1];

  // Setup RCTRootView with initialProperties
};

RCTAsyncLocalStorage *storage = [[RCTAsyncLocalStorage alloc] init];

dispatch_async(storage.methodQueue, ^{
  [storage performSelector:@selector(multiGet:callback:) withObject:@[@"theme"] withObject:completion];
});

You could additionally use dispatch_semaphore_wait to perform this synchronously

Update:

I needed the variable in the global state not just in the component props so the above doesn't go far enough.

I've had to work this into the React Native source at the point that the Javascript source is loaded.

NSString *javascriptPrepend = [NSString stringWithFormat:@"var ThemeMode = '%@';", self.theme];
NSMutableData *prependData = [[javascriptPrepend dataUsingEncoding:NSUTF8StringEncoding] mutableCopy];
[prependData appendData:sourceCode];

sourceCode = prependData; 

I'll see if they're open to a PR to allow this kind of functionality and post back here if I get it through.