Objective C location service geocode return values - ios

Question

I am trying to write a method that gets geocoding and returns the place mark as the methods return. I get the location manager portion; it waits to find an location, then runs stop updating. Then I run the geocoding and that is where I have the most questions. First what does that [] block notation mean? I can't seem to return anything out of that ever. So it gets the location in the place mark, but I want to pass that location info back out.
My goal is to have to buttons on a view, one that starts finding the location and writes the starting location to a table, and another button that gets the ending location and writes that to a table. I wanted to reuse the block of code that gets the location.
So in pseudo I want the action code for
button A
placemark objectFoo = call and get my location;
objectFoo write to DB or do whatever
Button B
placemark objectFoo = call and get my location;
objectFoo write to DB or do whatever
Coming from Java I'm confused by what that block of reverseGeocodeLocation:currentLocation is and how I can modify it? I envision an object that goes and gets my location and just hands that back to whatever called it to with it what I please.
- (CLPlacemark *)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSLog(#"didUpdateToLocation: %#", newLocation);
CLLocation *currentLocation = newLocation;
if (currentLocation != nil) {
_status.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.longitude];
NSLog(#"longitude: %#", [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.longitude]);
_status.text = [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.latitude];
NSLog(#"latitude: %#", [NSString stringWithFormat:#"%.8f", currentLocation.coordinate.latitude]);
}
// Stop Location Manager
[_locationManager stopUpdatingLocation];
NSLog(#"Resolving the Address");
[geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemarks, NSError *error) {
NSLog(#"Found placemarks: %#, error: %#", placemarks, error);
if (error == nil && [placemarks count] > 0) {
placemark = [placemarks lastObject];
_startLocation.text = [NSString stringWithFormat:#"%# %#\n%# %#\n%#\n%#",
placemark.subThoroughfare, placemark.thoroughfare,
placemark.postalCode, placemark.locality,
placemark.administrativeArea,
placemark.country];
NSLog(#"%#", placemark.subThoroughfare); // address number
NSLog(#"%#", placemark.thoroughfare); // address St
NSLog(#"%#", placemark.postalCode); // zip
NSLog(#"%#", placemark.locality); // city
NSLog(#"%#", placemark.administrativeArea); // state
NSLog(#"%#", placemark.country); // country
NSLog(#" debug county == %#", placemark.country); // country
} else {
NSLog(#"%#", error.debugDescription);
//return placemark;
}
//return placemark;
} ];
NSLog(#" needs to log this to see placemerk country == %#", placemark.country);
return placemark; //placemark object?
}

Answer 1

The [] notation in Objective C can mean a few things, but in this case I think you are referring to the method invocation on an object. So [myObject doSomethingWithInt:i]; is the same as myObject.doSomethingWithInt(i); in Java. Apple has a guide to Objctive c here and there are a number of other introductions and tutorials available on the info pages for the iOS and Objective-C tags here on SO.
In terms of responding to button presses, it is very similar to the event model in Java. You will need to establish a link between the buttons on your storyboard or xib and an event in your UIViewController instance. Again, it is best to work through some examples and tutorials, but essentially you
create a class that subclasses UIViewController
Declare IBAction methods in the .h file for your subclass
In the view in your storyboard or XIB file you set the view's controller class to your subclass
Once you add the buttons to the view you can then drag from the "touches up inside" event on the button to your View Controller and link it to the appropriate IBAction method.
Objective-C and iOS use the delegate pattern heavily. The method in your question is one of the delegate methods of the CLLocationmanagerDelegate protocol. You can declare some #property variables in the .h file for the class that contains this method and change it to something like -
In your .h file
#property (retain,nonatomic) CLPlacemark *currentPlacemark;
in your .m file
- (CLPlacemark *)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSLog(#"didUpdateToLocation: %#", newLocation);
CLLocation *currentLocation = newLocation;
if (currentLocation != nil) {
[geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemarks, NSError *error) {
NSLog(#"Found placemarks: %#, error: %#", placemarks, error);
if (error == nil && [placemarks count] > 0) {
self.currentPlacemark = [placemarks lastObject];
}
}
}
In your viewController subclass .h file
#property (strong,nonatomic) *MyLocationMonitor *locationMonitor;
In your ..m file
- (void) viewDidLoad
{
[super viewDidLoad];
self.locationMonitor=[[MyLocationMonitor alloc]init];
}
to expose the current location and then when the button is clicked you could do something like
-(IBAction)button1Clicked:(id)sender {
CLLocation *currentLocation=self.locationMonitor.currentPlacemark;
// TODO - Do something
}