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;


            }
        }

    }];
}