Question

While my end project is not another where did I park app. I thought this would be a good place to start to get a good grasp of MKMap and Locations.

Ok so I can set pins, see myself, and get my current location to show up in a label.

What I can’t do is:

A. On a button push
1) Store the users current location.
2) Drop a pin(red) in the current users location.
(So the new pin stays even if the user(blue) moves)

B. On a separate button push
1) Clear the pin of the users dropped pin(red) off the map.

I cannot seem to set the map annotation for the new pin in the button. The numbers change and the map does not refresh(i’m guessing) to show my pin with or with out the right set of coords in it.

This what I have so far. (NO SNICKERING) 😛

#import "Find_My_CarViewController.h"
#import "MapAnnotation.h"

@implementation Find_My_CarViewController

@synthesize CLController;
@synthesize hereIamLat;
@synthesize hereIamLong;
@synthesize mapView;

- (void)dealloc
{
    [hereIamLat release];
    [hereIamLong release];
    [CLController release];
    [super dealloc];
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];
    CLController = [[CoreLocationController alloc] init];
    CLController.delegate = self;
    [CLController.locMgr startUpdatingLocation];  
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

-(void)viewWillAppear:(BOOL)animated
{
    MKCoordinateRegion region;
    region.center.latitude =40.798356;
    region.center.longitude= -81.411158;
    region.span.longitudeDelta=0.3;
    region.span.latitudeDelta =0.3;
    [mapView setRegion:region animated:YES];   
}

- (void)locationUpdate:(CLLocation *)location
{
    latitudeLabel.text = [NSString stringWithFormat:@"LATITUDE: %f", location.coordinate.latitude];
    longitudeLabel.text = [NSString stringWithFormat:@"LONGITUDE: %f", location.coordinate.longitude];

    //hereIamLat = [NSString stringWithFormat:@"%g", location.coordinate.latitude];
    //hereIamLong = [NSString stringWithFormat:@"%g", location.coordinate.longitude];   
}

- (void)locationError:(NSError *)error
{
//speedLabel.text = [error description];
}

-(IBAction)PushToMark
{
    NSScanner *strLat = [NSScanner scannerWithString:latitudeLabel.text];
    double dblLat;
    [strLat scanDouble:&dblLat];
    NSScanner *strLong = [NSScanner scannerWithString:longitudeLabel.text];
    double dblLong;
    [strLong scanDouble:&dblLong];

    NSLog(@"lat: %f",dblLat);
    NSLog(@"long: %f",dblLong);
    MKCoordinateRegion location1;
    location1.center.latitude =dblLat;
    location1.center.longitude= dblLong;
    location1.span.longitudeDelta=0.1;
    location1.span.latitudeDelta =0.1;

    MapAnnotation *ann1 =[[[MapAnnotation alloc] init] autorelease];
    ann1.title=@"Here";
    ann1.subtitle=@"I AM";
    ann1.coordinate= location1.center;
    [mapView addAnnotation:ann1];
}

@end

Edit:
Ok so I went this route thanks.

#import "LocationTestViewController.h"
#import "CoreLocation/CoreLocation.h"
#import "MapAnnotation.h"

@implementation LocationTestViewController
@synthesize locationManager;
@synthesize mapView;

- (void)dealloc
{
[mapView release];
[locationManager release];
[super dealloc];
} 

- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
 [super viewDidLoad];
}
*/

- (void)viewDidUnload
{
[self setMapView:nil];
[self setLocationManager:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (IBAction)getLocation:(id)sender {


locationManager = [[CLLocationManager alloc] init];
locationManager.distanceFilter=kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
[locationManager startUpdatingLocation];

[mapView setMapType:MKMapTypeStandard];
[mapView setZoomEnabled:YES];
[mapView setScrollEnabled:YES];
MKCoordinateRegion region = {{0.0,0.0},{0.0,0.0}};
region.center.latitude = locationManager.location.coordinate.latitude;
region.center.longitude = locationManager.location.coordinate.longitude;
region.span.longitudeDelta = 0.005f;
region.span.latitudeDelta = 0.005f;
[mapView setRegion:region animated:YES];
[mapView setDelegate:sender];

MKCoordinateRegion location1;
location1.center.latitude =locationManager.location.coordinate.latitude;
location1.center.longitude= locationManager.location.coordinate.longitude;
location1.span.longitudeDelta=0.1;
location1.span.latitudeDelta =0.1;

MapAnnotation *ann1 =[[[MapAnnotation alloc] init] autorelease];
ann1.title=@"You Parked Here";
ann1.subtitle=@"";
ann1.coordinate= location1.center;
[mapView addAnnotation:ann1];

}
@end

Answer 1

Why not use a CLLocationCoordinate2D to store your current location when you get the delegate callback - (void)locationUpdate:(CLLocation *)location ? There’s no real reason to use an MKCoordinateRegion and NSScanner.

Do this instead:

- (void)locationUpdate:(CLLocation *)location
{
    latitudeLabel.text = [NSString stringWithFormat:@"LATITUDE: %f", location.coordinate.latitude];
    longitudeLabel.text = [NSString stringWithFormat:@"LONGITUDE: %f", location.coordinate.longitude];

    self.myLocation = location; // a property that stores the current location
}

Then in your - (IBAction)pushToMark you can create and add the annotation using self.myLocation as the coordinate property.

As for removing the annotation – see Mundi’s answer for that.