What is proper way to get ETA (estimated time arrival) from any location to my current location

Question

Would like to know what is proper way to get ETA (estimated time arrival) from any location to my current location, in consideration the following situation:

a. ex.

Answer 1

This worked for me using route.distance from M to the K's answer I was modifying code from this tutorial map directions tutorial

(IBAction)routeButtonPressed:(UIBarButtonItem *)sender {
    MKDirectionsRequest *directionsRequest = [[MKDirectionsRequest alloc] init];
    MKPlacemark *placemark = [[MKPlacemark alloc] initWithPlacemark:thePlacemark];
    [directionsRequest setSource:[MKMapItem mapItemForCurrentLocation]];
    [directionsRequest setDestination:[[MKMapItem alloc] initWithPlacemark:placemark]];
    directionsRequest.transportType = MKDirectionsTransportTypeAutomobile;
    MKDirections *directions = [[MKDirections alloc] initWithRequest:directionsRequest];
    [directions calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
        if (error) {
            NSLog(@"Error %@", error.description);
        } else {
            routeDetails = response.routes.lastObject;
            [self.mapView addOverlay:routeDetails.polyline];
            self.destinationLabel.text = [placemark.addressDictionary objectForKey:@"Street"];
            self.distanceLabel.text = [NSString stringWithFormat:@"%0.1f Miles", routeDetails.distance/1609.344];

            self.etaLabel.text = [NSString stringWithFormat:@"%0.1f minutes",routeDetails.expectedTravelTime/60];

            //self.transportLabel.text = [NSString stringWithFormat:@"%u" ,routeDetails.transportType];
            self.allSteps = @"";
            for (int i = 0; i < routeDetails.steps.count; i++) {
                MKRouteStep *step = [routeDetails.steps objectAtIndex:i];
                NSString *newStep = step.instructions;
                self.allSteps = [self.allSteps stringByAppendingString:newStep];
                self.allSteps = [self.allSteps stringByAppendingString:@"\n\n"];
                self.steps.text = self.allSteps;


            }
        }

    }];
}

Answer 2

I know this post is a bit old but in case someone is looking at the answer since iOS 7 Apple provide an API in MapKit in order to calculate all these info.

Here is a snippet of how to use this API

    MKDirectionsRequest *request = [[MKDirectionsRequest alloc] init];
    [request setSource:[MKMapItem mapItemForCurrentLocation]];
    [request setDestination:destination];
    [request setTransportType:MKDirectionsTransportTypeAutomobile];
    [request setRequestsAlternateRoutes:NO];
    MKDirections *directions = [[MKDirections alloc] initWithRequest:request];
    [directions calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
        if ( ! error && [response routes] > 0) {
            MKRoute *route = [[response routes] objectAtIndex:0];
            //route.distance  = The distance
            //route.expectedTravelTime = The ETA
        }
    }];