Executing synchronous queries to Google Cloud Endpoints on iOS

Question

I guess this is really a feature request to Google, but I'm curious if anyone knows a work around. I'd like to execute a synchronous query request to a GAE Endpoints api.

In Android executing a request is synchronous. Then you put it into an AsyncTask to make it work in the background.

In iOS executing a request is asynchronous. You simply pass in a callback block.

I'm converting an Android app into an iOS app and it'd be really nice if they used the same mechanism. For example there are times when I WANT a synchronous query. It just makes my code easier and I know to put it on a background thread.

So my question is this... is there any way (hacky or not) to block until the iOS query completes?

Answer 1

You can wait on the call to finish with code with a timeout using code similar to this. Obviously you wouldn't want to do this on a UI thread but this would ensure your completion handlers run in serial.

NSLog(@"Before API Call");
GTLServiceTicket *apiCall = [apiService executeQuery:query completionHandler:^(GTLServiceTicket *ticket,
                                                   GTLHelloworldHelloGreeting *object,
                                                   NSError *error) {
    NSLog(@"Starting completion handler");
    NSArray *greetings = [NSArray arrayWithObjects: object, nil];
    greetingsRetrievedFromAPI = greetings;
    [self performSegueWithIdentifier: @"DisplayGreetings" sender: self];
    NSLog(@"Ending completion handler");
}];
[apiService waitForTicket:apiCall timeout:100000 fetchedObject:nil error:nil];
NSLog(@"After completion handler");