It seems that I'm running into a delegate issue when using regions with CLLocationManager. When I first run the project, I add various regions to the manager and call requestStateForRegion: to determine if I'm currently within any of them. The manager then calls my didDetermineState: function (rather quickly it seems) but all of the passed CLRegionStates are unknown.
When I go into the Maps app and find my current location, then relaunch my application within a few minutes, the states are found correctly.
I've set about 10 regions where one of which is my hard-coded current location, but my current location still shows as unknown. Any ideas?
manager = [[CLLocationManager alloc] init];
manager.delegate = self;
if ([manager respondsToSelector:#selector(requestAlwaysAuthorization)]) {
[manager requestAlwaysAuthorization];
}
for (CLRegion *monitored in [manager monitoredRegions]) {
[manager stopMonitoringForRegion:monitored];
}
NSArray *events = ...;
for (Event *event in events) {
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(latitude, longitude);
CLRegion *region = [[CLRegion alloc] initCircularRegionWithCenter:coord radius:50.0 identifier:[NSString stringWithFormat:#"%#", event.eventID]];
[manager startMonitoringForRegion:region];
}
Related
There are two classes that help regarding map plotting and determining user location - MKMapView and CLLocationManager.
MKMapView has a delegate “didUpdateUserLocation” that tells the user’s current location. At the same time, CLLocationManger has a delegate “didUpdateToLocation” and it also does the same thing.
My question is when to use MKMapView and CLLocationManager. I am able to get current location of the device from MKMapView then why and when should I use CLLocationManager? I tried to get it but I am still not sure.
I think you are confusing the MKMapView property showsUserLocation with CLLocationManager.
As a convenience MKMapView's allow you to simply enable a property to show the users current location on the map UI. This is really handy if you only need to show the user where they are on a map.
However, there are demonstrably many other use cases where simply showing location on a map is not enough and this is where CLLocationManager comes in.
Consider for example a running/training application, where a record of user locations is required to calculate running distance, or even an example from one of my own applications, where by I needed to find the users location (lat/long) to calculate distance to various train stations in real time to identify which was closest for the user. In these examples there is no need for a MapView so using a LocationManager is the right choice.
Anytime you need to programmatically interact with the users location and don't require a map UI basically!
I prefer to use CLLocationManager which is used internally by the MKMapView, so if you don't need to use the map, just use the below code from the location manager.
locationManager = [[CLLocationManager alloc] init];
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.delegate = self;
[locationManager startUpdatingLocation];
Just don't forget to store the locationManager instance somewhere in your class and you can implement the delegate like this.
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
NSLog(#"Error detecting location %#", error);
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
CLLocation* location = (CLLocation*)locations.lastObject;
NSLog(#"Longitude: %f, Latitude: %f", location.coordinate.longitude, location.coordinate.latitude);
}
EDIT
You can get the address of the user based on their location using Apple's Geo coder
// Use Apple's Geocoder to figure the name of the place
CLGeocoder* geoCoder = [[CLGeocoder alloc] init];
[geoCoder reverseGeocodeLocation:location completionHandler: ^(NSArray* placemarks, NSError* error) {
if (error != nil) {
NSLog(#"Error in geo coder: %#", error);
}
else {
if (placemarks.count == 0) {
NSLog(#"The address couldn't be found");
}
else {
// Get nearby address
CLPlacemark* placemark = placemarks[0];
// Get the string address and store it
NSString* locatedAt = [[placemark.addressDictionary valueForKey:#"FormattedAddressLines"] componentsJoinedByString:#", "];
location.name = locatedAt;
NSLog(#"The address is: %#", locatedAt);
}
}
}];
I have researched on how to get location data from images returned from UIImagePickerController camera. However, I think that the easiest way is to get the current location from CLLocationManager at the instant UIImagePickerController captures an image.
Is there a way of doing this? Is there a way of listening for the "capturePhoto" event, for example?
Just to clarify, the users using my app will likely be moving pretty fast.
Here's what I'd recommend so you don't track the user's location any more than you have to and so you get the user's location closest to the time the image was actually snapped.
Instantiate the CLLocationManager class variable in your viewDidLoad, ex:
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
And make sure it's authorized:
if ([CLLocationManager authorizationStatus] != kCLAuthorizationStatusAuthorizedWhenInUse) {
[self.locationManager requestWhenInUseAuthorization];
}
(Also include the "NSLocationWhenInUseUsageDescription" key in the .plist)
Then you could wait until the UIImagePickerController is actually presented before (1) initializing the dictionary to hold the locations and (2) starting to update the location, ex:
[self presentViewController:self.imagePicker animated:YES completion:nil];
self.locationDictionary = [[NSMutableDictionary alloc] init];
[self.locationManager startUpdatingLocation];
At that point, you can start storing the user's updated locations in an NSMutableDictionary self.locationDictionary class instance variable when CLLocation values are returned from the didUpdateToLocation delegate method, ex:
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
// Format the current date time to match the format of
// the photo's metadata timestamp string
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"YYYY:MM:dd HH:mm:ss"];
NSString *stringFromDate = [formatter stringFromDate:[NSDate date]];
// Add the location as a value in the location NSMutableDictionary
// while using the formatted current datetime as its key
[self.locationDictionary setValue:newLocation forKey:stringFromDate];
}
And then once the image is selected, find its timestamp in the metadata and find the value in the location dictionary with a timestamp key closest to the image timestamp, ex:
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
[self.locationManager stopUpdatingLocation];
// When a photo is selected save it as a UIImage
self.selectedPhoto = info[UIImagePickerControllerOriginalImage];
// Get the timestamp from the metadata and store it as an NSString
self.selectedPhotoDateTime = [[[info valueForKey:UIImagePickerControllerMediaMetadata] objectForKey:#"{Exif}"] objectForKey:#"DateTimeOriginal"];
// If the CLLocationManager is in fact authorized
// and locations have been found...
if (self.locationDictionary.allKeys.count > 0) {
// Sort the location dictionary timestamps in ascending order
NSArray *sortedKeys = [[self.locationDictionary allKeys] sortedArrayUsingSelector: #selector(compare:)];
// As a default, set the selected photo's CLLocation class
// variable to contain the first value in the sorted dictionary
self.selectedPhotoLocation = [self.locationDictionary objectForKey:[sortedKeys objectAtIndex:0]];
// Then go through the location dictionary and set the
// photo location to whatever value in the dictionary
// has a key containing a time most closely before
// the image timestamp. Note that the keys can be compared
// as strings since they're formatted in descending order --
// year to month to day to hour to minute to second.
for (NSString *key in sortedKeys) {
// If the photo's metadata timestamp is less than or equal to
// the current key, set the selected photo's location class
// variable to contain the CLLocation value associated with the key
if ([self.selectedPhotoDateTime compare:key] != NSOrderedAscending) {
self.selectedPhotoLocation = [self.locationDictionary objectForKey:key];
}
// Else if the time in the location dictionary is past
// the photo's timestamp, break from the loop
else {
break;
}
}
}
[self dismissViewControllerAnimated:YES completion:nil];
}
In your .h file you need to add the following to your code:
#interface TakePhotoViewController : UIViewController <CLLocationManagerDelegate>
In your .m file you need the following.
#interface TakePhotoViewController (){
//location stuff
CLLocationManager * manager;
CLGeocoder *geocoder;
CLPlacemark * placemark;
}
The above code set's up relevant references to find your location.
Next add this to your viewDidLoad method:
manager = [[CLLocationManager alloc] init];
geocoder = [[CLGeocoder alloc] init];
This initialises the Location Manager and Geocoder.
Then in your code that either initiates taking a picture or returns the picture to a view use this:
manager.delegate = self;
manager.desiredAccuracy = kCLLocationAccuracyBest;
[manager startUpdatingLocation];
To stop the continuous updating of the location add this to your imagePickerReturn method:
[manager stopUpdatingLocation];
As soon as you stop updating the location you will be saving the very last location that was updated. The location updates once every .5 - 1 second, so even if you are moving or have the camera open for a long time it will only store the location of whatever image you pick. To save the date (which includes time down to milliseconds) use:
NSDate * yourCoreDataDateName = [NSDate date];
For good coding practice to handle any errors you will need this:
//handles the error if location unavailable
- (void) locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error{
NSLog(#"Error: %#", error);
NSLog(#"Failed to get location... :-(");
}
- (void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{
NSLog(#"Location: %#", newLocation);
CLLocation * currentLocation = newLocation;
self.locationTF.text = #"Finding Location...";
if (currentLocation != nil){
[geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemarks, NSError *error) {
if (error == nil && [placemarks count] > 0){
placemark = [placemarks lastObject];
//the code below translates the coordinates into readable text of the location
self.locationLabel.text = [NSString stringWithFormat:#"%# %# , %#, %#, %# %#", placemark.subThoroughfare, placemark.thoroughfare, placemark.locality, placemark.administrativeArea, placemark.country, placemark.postalCode];
}
else{
NSLog(#"%#", error.debugDescription);
self.locationLabel.text = #"Failed to find location";
}
}];
}
}
I must warn you that iOS8 will throw NO error when it can't find a location because it needs you as the programmer to add an alert view to authorise getting locations. See this tutorial on how to overcome this issue:
http://nevan.net/2014/09/core-location-manager-changes-in-ios-8/
I got this tutorial from the most popular asked question about the new error.
The most accurate way to do this would be through the exif metadata. Have a look at this post by Ole Begemann on how to do this.
UPDATE
It seems like Apple doesn't include the location to the metadata to images taken with the Camera from the UIImagePicker.
Another option to get the location in which the image was taken would be to use a custom overlay view for the UIImagePicker and get the location when the takePicture method is called. This would probably achieve the best result.
I am working on the mapkit in ios where I have to trace my route from my current location.
Now, I had assigned my current location i.e. latitude and longitude using the simulator(Debug->location->custom location) but when I try to trace my source I get my source location as nil and due to which I am not able to get the route.
[directionsRequest setSource:[MKMapItem mapItemForCurrentLocation]];
Can any one suggest the possible solution for my problem
Code
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];
If you are using MapView then there is one delegate method in which you will get your current location without using CLLocationManager.
-(void)viewDidLoad
{
mapView.delegate=self;
}
-(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
`enter code here` //Here MKUserLocation will give you current Location and every time will method will call when the location is change...'
}
and if you want only user location then use
MKUserLocation *userlocation=mapView.userlocation
I think you are getting nil location because you are testing it in simulator please run it on real device
https://developer.apple.com/library/ios/documentation/MapKit/Reference/MKMapItem_class/ states mapItemForCurrentLocation does not contain coordinate data for privacy reasons, but here is a simple workaround if you are using a map view and showsUserLocation true:
MKUserLocation* userLocation = self.mapView.userLocation;
MKMapItem* mapItemForCurrentLocation;
if(userLocation.isUpdating && userLocation.isBeingUpdated){
mapItemForCurrentLocation = [[MKMapItem alloc] initWithPlacemark:[[MKPlacemark alloc] initWithCoordinate:userLocation.location.coordinate addressDictionary:nil]];
mapItemForCurrentLocation.name = #"Current Location";
}
What I want to accomplish in my app is to get the current user location and display it onscreen in a UILabel. I would like to have an NSString of current user's location with a format similar to this: #"City, State/Country". It would be a one-time operation at the start of the app launch.
I have no prior experience with location in iOS and I would like to get some advice on this one - I'm sure it's quite a simple task.
The process is as follows:
Add CoreLocation.framework to your project. See Linking to a Library or a Framework. If you want to use the address book constants that I use below, you might want to add the AddressBook.framework to your project, too.
Start location services. For this purpose, the "significant change" service (less accurate, but lower power consumption) is probably sufficient for city-level accuracy.
When the location manager informs you of the user's location, then perform a reverse geocode of that location.
Stop location services.
Thus, that might look like:
#import <CoreLocation/CoreLocation.h>
#import <AddressBook/AddressBook.h>
#interface ViewController () <CLLocationManagerDelegate>
#property (nonatomic, strong) CLLocationManager *locationManager;
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self startSignificantChangeUpdates];
}
- (void)startSignificantChangeUpdates
{
if ([CLLocationManager locationServicesEnabled])
{
if (!self.locationManager)
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager startMonitoringSignificantLocationChanges];
}
}
- (void)stopSignificantChangesUpdates
{
[self.locationManager stopUpdatingLocation];
self.locationManager = nil;
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *location = [locations lastObject];
CLGeocoder *geocoder = [[CLGeocoder alloc] init];
[geocoder reverseGeocodeLocation:location completionHandler:^(NSArray *placemarks, NSError *error) {
CLPlacemark *placemark = placemarks[0];
NSDictionary *addressDictionary = [placemark addressDictionary];
NSString *city = addressDictionary[(NSString *)kABPersonAddressCityKey];
NSString *state = addressDictionary[(NSString *)kABPersonAddressStateKey];
NSString *country = placemark.country;
self.label.text = [NSString stringWithFormat:#"%#, %#, %#", city, state, country];
}];
[self stopSignificantChangesUpdates];
}
Note, the location manager's notification of the location is contingent upon the user electing to share that with your app and will happen, even in the best case scenario, asynchronously. Likewise the reverse geocode happens asynchronously.
See Getting User Location from the Location Awareness Programming Guide.
Use -reverseGeocodeLocation:completionHandler: of CLGeocoder.
Try this code snippet, the only trick is that the CLPlacemark (see the Documentation for available info) you get back from the Geocoder has a bunch of info which isn't always consistent, this was one of my tries from an older project, trying to test for location, street name etc... test with your usage case to find a good match:
- (void)getLocationStringForCoordinates:(CLLocationCoordinate2D)coordinates {
if ( CLLocationCoordinate2DIsValid(coordinates) ) {
CLLocation *photoLocation = [[CLLocation alloc] initWithLatitude:coordinates.latitude longitude:coordinates.longitude];
CLGeocoder *geocoder = [[CLGeocoder alloc] init];
[geocoder reverseGeocodeLocation:photoLocation
completionHandler:^(NSArray *placemarks, NSError *error) {
CLPlacemark *locationPlacemark = [placemarks lastObject];
// Location (popular name, street, area)
NSString *location = locationPlacemark.subLocality ? locationPlacemark.subLocality : (locationPlacemark.name ? locationPlacemark.name : locationPlacemark.thoroughfare);
// sometimes the location can be the same
// as the city name (for small villages), if so
// make sure location is nil to skip it
// else if
// the location name is not being used but is very short 9less then 20 letters, use that instead
if([locationPlacemark.name isEqualToString:locationPlacemark.locality] && [location isEqualToString:locationPlacemark.name])
location = #"";
else if ( ![locationPlacemark.name isEqualToString:location] && locationPlacemark.name.length < 20 )
location = locationPlacemark.name;
// city
NSString *city = locationPlacemark.subAdministrativeArea ? locationPlacemark.subAdministrativeArea : locationPlacemark.locality;
city = city.length > 0 ? [#", " stringByAppendingString:city] : city;
NSString *locationName = [NSString stringWithFormat:#"%#%#", location, city];
}];
}
}
I've found a really nice and simple to follow tutorial on this topic - http://www.appcoda.com/how-to-get-current-location-iphone-user/
Hope it will be helpful to others!
Take a look at the reverseGeocodeLocation:completionHandler: method for CLGeocoder:
http://developer.apple.com/library/ios/#documentation/CoreLocation/Reference/CLGeocoder_class/Reference/Reference.html#//apple_ref/doc/uid/TP40009573
First you will have to use a CLLocationManager to get a CLLocation representing the user's current position.
I am trying to Reverse geocode location from Lat/Long value that I get earlier in the App and I would like from this coordinate to find the city name, country name and ISO.
I am currently using CLLocationManager to get actual location information with the folowing code:
//Auto geolocation and find city/country
locationManager.delegate=self;
//Get user location
[locationManager startUpdatingLocation];
[self.geoCoder reverseGeocodeLocation: locationManager.location completionHandler:
^(NSArray *placemarks, NSError *error) {
//Get nearby address
CLPlacemark *placemark = [placemarks objectAtIndex:0];
//String to hold address
locatedAtcountry = placemark.country;
locatedAtcity = placemark.locality;
locatedAtisocountry = placemark.ISOcountryCode;
//Print the location to console
NSLog(#"Estas en %#",locatedAtcountry);
NSLog(#"Estas en %#",locatedAtcity);
NSLog(#"Estas en %#",locatedAtisocountry);
[cityLabel setText:[NSString stringWithFormat:#"%#,",locatedAtcity]];
[locationLabel setText:[NSString stringWithFormat:#"%#",locatedAtcountry]];
//Set the label text to current location
//[locationLabel setText:locatedAt];
}];
It is working perfectly but, It is possible to do the same from Long/Lat value that I had already saved in the device and not with the current location like on the actual code ?
Update and solution:
Thanks Mark for the answer, I finally use the following code to get info from saved coordinate:
CLLocation *location = [[CLLocation alloc] initWithLatitude:37.78583400 longitude:-122.40641700];
[self.geoCoder reverseGeocodeLocation: location completionHandler:
^(NSArray *placemarks, NSError *error) {
//Get nearby address
CLPlacemark *placemark = [placemarks objectAtIndex:0];
//String to hold address
locatedAtcountry = placemark.country;
locatedAtcity = placemark.locality;
locatedAtisocountry = placemark.ISOcountryCode;
//Print the location to console
NSLog(#"Estas en %#",locatedAtcountry);
NSLog(#"Estas en %#",locatedAtcity);
NSLog(#"Estas en %#",locatedAtisocountry);
[cityLabel setText:[NSString stringWithFormat:#"%#",locatedAtcity]];
[locationLabel setText:[NSString stringWithFormat:#"%#",locatedAtcountry]];
//Set the label text to current location
//[locationLabel setText:locatedAt];
}];
Yes. Create a CLLocation object using the initWithLatitude:longitude: method using your saved lat/lon values, and pass that to reverseGeocodeLocation:.
I am surprised that you say this is working (although, if you're on the simulator, location services are simulated anyway, which might be the reason) because when you call startUpdatingLocation, your implementation of CLLocationManagerDelegate methods like locationManager:didUpdateToLocation:fromLocation: get called. (You've implemented these right?) It is only when this (and other) delegate method is called that you can be certain that you have successfully determined the user's location.
You may want to read up on the CLLocationManagerDelegate protocol and on Location Services best practices as documented by Apple.