Current Location Button

[MrPeanutz90]

Hi All,

I need some help/advice on the userLocation function. I'm not sure how to use that function on a button. Currently, i could see my current location on a map view. I've created a custom button called UserClickCLButton. If the user were to scroll elsewhere on the map, the user would be animated back to the current location blue dot when the button is clicked.

I need some help for my coding, any help would be great! Thanks!
The following below is my code:

-(IBAction) UserClickCLButton
{
MKCoordinateRegion newRegion;

newRegion.center. = ?
OR
userLocation = ?

newRegion.span.latitudeDelta = 0.23;
newRegion.span.longitudeDelta = 0.23;

[mapView setRegion:newRegion animated:YES];
}

[Duncan C]

Originally Posted by MrPeanutz90

Hi All,

I need some help/advice on the userLocation function. I'm not sure how to use that function on a button. Currently, i could see my current location on a map view. I've created a custom button called UserClickCLButton. If the user were to scroll elsewhere on the map, the user would be animated back to the current location blue dot when the button is clicked.

I need some help for my coding, any help would be great! Thanks!
The following below is my code:

-(IBAction) UserClickCLButton
{
MKCoordinateRegion newRegion;

newRegion.center. = ?
OR
userLocation = ?

newRegion.span.latitudeDelta = 0.23;
newRegion.span.longitudeDelta = 0.23;

[mapView setRegion:newRegion animated:YES];
}

You've got the right idea.

You need to have a location manager active and generating location updates. When you receive a location update through locationManager:didUpdateToLocation:fromLocation:, save the location information in an instance variable.

Then, when the user clicks the "show current location" button, use the saved lat/long in your code above.

An alternative to this would be to ask your map view for it's userLocation property, and then get the coordinate property of the user location.

[MrPeanutz90]

Originally Posted by Duncan C

You've got the right idea.

You need to have a location manager active and generating location updates. When you receive a location update through locationManager:didUpdateToLocation:fromLocation:, save the location information in an instance variable.

Then, when the user clicks the "show current location" button, use the saved lat/long in your code above.

An alternative to this would be to ask your map view for it's userLocation property, and then get the coordinate property of the user location.

Thanks for the comment, so do I just need to use back the current "locationManager:didUpdateToLocation:fromLocation: "
which is in my code already? how do I save the information? Is it something like "region.center = newLocation.coordinate" below?

So after that I would just place my button method, "(IBAction) UserClickCLButtton" after the locationManager method?

//Current locationManager updating the map

- (void) locationManagerCLLocationManager *) manager
didUpdateToLocationCLLocation *) newLocation
fromLocationCLLocation *) oldLocation {
//---update the map---
MKCoordinateRegion region;
MKCoordinateSpan span;
span.latitudeDelta = .025;
span.longitudeDelta = .025;

region.center = newLocation.coordinate;
region.span = span;
[mapView setRegion:region animated:YES];
}

I would like to know about the alternative where I could use the map view's userLocation property. Do I need to declare the MKUserLocation class on the .h file? And then in my .m file, I would declare it as mapView.userLocation = userLocation.coordinate?

[Duncan C]

Originally Posted by MrPeanutz90

Thanks for the comment, so do I just need to use back the current "locationManager:didUpdateToLocation:fromLocation: "
which is in my code already? how do I save the information? Is it something like "region.center = newLocation.coordinate" below?

So after that I would just place my button method, "(IBAction) UserClickCLButtton" after the locationManager method?

//Current locationManager updating the map

- (void) locationManagerCLLocationManager *) manager
didUpdateToLocationCLLocation *) newLocation
fromLocationCLLocation *) oldLocation {
//---update the map---
MKCoordinateRegion region;
MKCoordinateSpan span;
span.latitudeDelta = .025;
span.longitudeDelta = .025;

region.center = newLocation.coordinate;
region.span = span;
[mapView setRegion:region animated:YES];
}

I would like to know about the alternative where I could use the map view's userLocation property. Do I need to declare the MKUserLocation class on the .h file? And then in my .m file, I would declare it as mapView.userLocation = userLocation.coordinate?

I told you how to save the location. Create an instance variable (called something like currentCoordinate) in your map view delegate of type CLLocationCoordinate2D.

In your didUpdateToLocation method, save the newLocation.coordinate to currentCoordinate.

Finally, in your code that handles the button press, use currentCoordinate as the region center that you pass to setRegion.

Slow down, read the documentation on MKMapView and CLLocationManager, and look through some of the sample apps that come with XCode. It's very well documented, and there are a number of good examples apps included. It takes some time and study to understand how it works and how to use it.

You might want to download and try our company's location bookmarking app, Save My Place. (The iPhone version is only $0.99.) In our app, we have a checkbox that lets you ask to show your current location. When you check it, the app scrolls the map when the user's location gets too close to the edge of the map. It will also scroll the map to keep both your current location and your selected destination on-screen, if you ask to show both. We do all that by setting flags based on the state of "show location" and "show destination" checkboxes, and then deciding how to respond to location manager updates based on the state of the flags and the current map span.

[MrPeanutz90]

Originally Posted by Duncan C

I told you how to save the location. Create an instance variable (called something like currentCoordinate) in your map view delegate of type CLLocationCoordinate2D.

In your didUpdateToLocation method, save the newLocation.coordinate to currentCoordinate.

Finally, in your code that handles the button press, use currentCoordinate as the region center that you pass to setRegion.

Slow down, read the documentation on MKMapView and CLLocationManager, and look through some of the sample apps that come with XCode. It's very well documented, and there are a number of good examples apps included. It takes some time and study to understand how it works and how to use it.

You might want to download and try our company's location bookmarking app, Save My Place. (The iPhone version is only $0.99.) In our app, we have a checkbox that lets you ask to show your current location. When you check it, the app scrolls the map when the user's location gets too close to the edge of the map. It will also scroll the map to keep both your current location and your selected destination on-screen, if you ask to show both. We do all that by setting flags based on the state of "show location" and "show destination" checkboxes, and then deciding how to respond to location manager updates based on the state of the flags and the current map span.

Hi Duncan,

I've followed your instructions and created my instance variable, currentCoordinate (CLLocationCoordinate2D) inside my .h file.

@interface MapView : UIViewController
<CLLocationManagerDelegate, MKMapViewDelegate, MKReverseGeocoderDelegate>
{
IBOutlet UITextField *accuracyTextField;
IBOutlet UITextField *latitudeTextField;
IBOutlet UITextField *longitudeTextField;
CLLocationManager *lm;

CLLocationCoordinate2D currentCoordinate;

}

AND THEN, I save the newLocation.coordinate to currentCoordinate as you've stated.


- (void) locationManagerCLLocationManager *) manager
didUpdateToLocationCLLocation *) newLocation
fromLocationCLLocation *) oldLocation {

newLocation.coordinate = currentCoordinate;

AND LASTLY, I use the currentCoordinate as the newRegion.center, is that right?

-(IBAction) UserClickCLButton
{

MKCoordinateRegion newRegion;

newRegion.center = currentCoordinate;

newRegion.span.latitudeDelta = 0.23;
newRegion.span.longitudeDelta = 0.23;

[mapView setRegion:newRegion animated:YES];
}

BUT, it stills shows me and error stated :

newLocation.coordinate = currentCoordinatel -"object cannot be set - either readonly property or no setter found"

[timle8n1]

Dude use CODE tags!

- (void) locationManager:(CLLocationManager *)manager 
    didUpdateToLocation:(CLLocation *)newLocation 
    fromLocation:(CLLocation *)oldLocation {
  currentCoordinate = newLocation.coordinate
}