CLGeocoder only returns first look up result

Question

I'm experiencing a weird issue with - (void)geocodeAddressString:(NSString *)addressString completionHandler:(CLGeocodeCompletionHandler)completionHandler;.

I have a list of locations need to be looked up. So I did something like

for (Trip *trip in takenTrips) {
    [geoCoder geocodeAddressString:trip.location completionHandler:^(NSArray *placemarks, NSError *error) {
        //handling result
    }];
}

But it seems the completion handler is only being called once. I tried making these lookups sequentially. Then everything works fine.

I searched around for a while, but couldn't find anything similar to this. I'm totally baffled here...

Any suggestion is welcomed!

Answer 1

Applications should be conscious of how they use geocoding. rules of thumb for using this class effectively: Send at most one geocoding request for any one user action. class link

To solve your problem you could the one of the following:

1. Do-while loop that checks if geocoder is processing geocoding
2. NSOperationQueue to excucute one at time if it complete
3. in the completeHandle execute a callback that run the next geocode

Answer 2

Why don't you use more geocoder?

dispatch_queue_t geocoderQueue = dispatch_queue_create("geocoder.queue", DISPATCH_QUEUE_CONCURRENT); 
dispatch_apply([takenTrips count], dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ull), ^(size_t index) {

    NSString *loc = [(Trip *)takenTrips[index] location];

    CLGeocoder *geoCoder = [CLGeocoder new];
    [geoCoder geocodeAddressString:loc completionHandler:^(NSArray *placemarks, NSError *error) {
        CLPlacemark *placemark = [placemarks firstObject];
        NSLog(@"%@",placemark.postalCode);
    }];
});

and also in a private concurrent queue so you can have a great result in performance.