Here is my code:
- (void) viewWillAppear:(BOOL)animated
{
// SETUP THE LOCATION MANAGER.
self.locManager = [[CLLocationManager alloc] init];
self.locManager.delegate = self;
[self.locManager startUpdatingLocation];
}
- (void) viewWillDisappear:(BOOL)animated
{
[self.locManager stopUpdatingLocation];
[self.locManager.delegate release];
}
When the View Controller exits the CLLocationManager arrow logo in the top right corner is still showing. This is both on iOS 4.3 and 5.0. Any explanation?
I believe the system indicates the location badge on any app that has used Core Location in last hour or so.
The purple arrow should disappear as soon as you call:
[self.locManager stopUpdatingLocation];
While allocating your locManager, you need not call self.locManager. That will bump up the retain count to 2. Instead use:
locManager = [[CLLocationManager alloc] init];
Also, put a breakpoint in your viewWillDisappear: method and make sure it does get called. Also, set the delegate to nil at the end.
After following these points, your code shall work.
The purple arrow is for Location Services and consumes battery heavily. Make sure the arrow disappears as soon as you call stopUpdatingLocation:
Related
I'm trying a lot of things to stop the location update of my app but nothing seems work…
What I do (regard of the post : StopUpdatingLocation method not working for iOS5) :
// Initialise my locationManager and start monitoring :
locationManager = [[CLLocationManager alloc] init];
[locationManager startUpdatingLocation];
// .. Some code to use the coordinates that locationManager gives me.
// To stop monitoring :
locationManager = nil;
You have to know I placed [locationManager stopUpdatingLocation]; in the method :
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
So the location is updated only 1 time (btw tell me if it's a good idea…).
I also tried to place [locationManager stopUpdatingLocation]; just before locationManager = nil; in the main code, but the blue dot that gives me my location is still moving on my map in both cases…
I also set a timer which print the locationManager object in the console, and it gives me (null) meanwhile the blue dot is still moving on my iPhone 5 so I don't understand that…
Or maybe the dot is still moving because of another thing, but not because of locationManager update ?
I'm certainly missing something but I don't get what :/.
Thanks for ideas and help.
One possibility: The blue dot moving on your map is because you set the MKMapView's showsUserLocation to YES. It will track until you set it to NO.
Another possibility: This line is wrong:
locationManager = nil;
That does not stop monitoring, but it does cause you to be unable to refer to the location manager, so now you can't stop monitoring! Cut that line.
I faced the same problem that even after I placed the code
[locationManager stopUpdatingLocation];
locationManager=nil;
my application was using GPS service which was un-necessarily consuming battery power. the solution for this problem is to turn off the showUserLocation property of MKMapView .
[self.mapView setShowsUserLocation:NO];
Since the MKMapView keeps on using your GPS service even if the LocationManager is nil.
Hope it will help you
Use this lines of code
[self.locationManager stopUpdatingLocation];
self.locationManager.delegate = nil;
self.locationManager = nil;
Thanks!
I have this problem:
Here is a part of my appDelegate file where I create a "performSelectorInBackground" method.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[self addSplash];
[self getLocation];
[self performSelectorInBackground:#selector(backgroundOp) withObject:nil];
return YES;
}
First I add some splash screen, the I get a location and the call background method.
This is content of background method:
- (void) backgroundOp
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
[self createEditableCopyOfDatabaseIfNeeded];
[self initTempData];
[self initApp];
[self checkDataVersion];
}
[self setAppStrings];
[self performSelectorOnMainThread:#selector(resultOp) withObject:nil waitUntilDone:YES];
[pool release];
}
I download some data, check version of data, setup strings for application and the call on main thread method to create a tab bar controller code here:
- (void) resultOp
{
tabBarController.delegate = self;
[self.window addSubview:tabBarController.view];
[self addTabBarArrow];
[self.window makeKeyAndVisible];
[self removeSplash];
}
Here I create a tab bar controller and remove splash screen. Then start my firstViewController.
Problem is that in my firstViewController I show a current location, but it is wrong. Sometimes is correct but very often is wrong.
Where is a problem ? Is there any option how to check if background thread end ? Or something other solution for my problem (I need only: show splash with activity indicator and some messages (this messages are changed in method e.g. init, get location etc.), then I need get location, the remove splash and show firstViewController) ... thanks a lot
Edit: Here is code for location:
- (void) getLocation
{
splashScreenController.splashLabel.text = #"Localization ...";
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kDistanceFilter;
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
[locationManager startUpdatingLocation];
}
Keep in mind, that the longer the location update runs, the more accurate it gets. The first 'hit' for the location isn't always the best one (most of the time it is the wrong one).
Maybe you could show your code where you have the events of the CLLocationManager.
Also, how much is the wrong position off of the right position? I think the AGPS thing first quickly checks its location by using WiFi hotspots nearby and after that gets more accurate by using the GPS chip.
Wherever you are using the location you acquire (which I can't really see from the code you posted), you should have checks on the horizontalAccuracy property of the newLocation you are receiving (and verticalAccuracy as well if altitude matters). You can say something like
if(newLocation.horizontalAccuracy < 100) {
//do something with newLocation
//because it is accurate to 100 meters
}
If you do not do these types of checks, you can get some really inaccurate locations, up to three or four kilometers from your real location at first.
Also, when using multiple threads, data integrity can sometimes become a problem. You need to make sure that variables are not being accessed and changed at the same time in multiple methods, or who knows if you will get the correct output.
Also, it is important to note that all of the methods called within backgroundOp will also be preformed in the background, even without explicitly calling them that way. Use
[self performSelectorOnMainThread:foo withObject:foobar waitUntilDone:NO];
to return to the main thread.
Edit:
viewDidLoad {
[super viewDidLoad];
iterations = -5;
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation
*)newLocation fromLocation:(CLLocation *)oldLocation {
iterations++;
if(iterations > 0) {
if(newLocation.horizontalAccuracy < 50) {
//do something with location with radius of uncertainty
//of less than 50
}
}
I'm using MKMapView and I start the map at the last known location with CLLocationManager, the problem is that the iPhone and Location Services reports that I'm still using the services after I'm done which rises some concerns about battery usage.
So, please help me release this properly.
CLLocationManager * MANG = [[CLLocationManager alloc] init];
[MANG startMonitoringSignificantLocationChanges];
if(MANG.location){
[mapa setCenterCoordinate:MANG.location.coordinate animated:NO];
}
[MANG stopMonitoringSignificantLocationChanges];
[MANG stopUpdatingLocation];
[MANG release];
There are two ways to fetch the location using Location Services: the first one, less accurate but more battery friendly; and the second one more accurate.
When you declare [myLocationManager startMonitoringSignificantLocationChanges] your iPhone checks for location every time you left a cell tower and enter into a new one.
When you declare [myLocationManager startUpdatingLocation] your iPhone checks for location every time the GPS detects a position change (maybe each 1-3 meters, depending on accuracy).
So the thing is, in your code you’re trying to stop the declared Location Manager twice. Just remove the second stop instruction and you’ll get the correct code:
CLLocationManager * MANG = [[CLLocationManager alloc] init];
[MANG startMonitoringSignificantLocationChanges];
if(MANG.location){
[mapa setCenterCoordinate:MANG.location.coordinate animated:NO];
}
[MANG stopMonitoringSignificantLocationChanges];
[MANG release];
I have a MKMapView whereby I drop an annotation everytime the view loads, or when showLocation custom class method is called.
I need the accuracy to be the best
-(void)viewDidLoad {
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
[locationManager startUpdatingLocation];
}
-(IBAction) showLocation:(id) sender{
[locationManager startUpdatingLocation];
}
- (void) locationManager:(CLLocationManager *) manager
didUpdateToLocation:(CLLocation *) newLocation
fromLocation:(CLLocation *) oldLocation {
// start geocoding with newLocation coordinate which will automatically set annotation.
SVGeocoder *geocodeRequest = [[SVGeocoder alloc]
initWithCoordinate:CLLocationCoordinate2DMake(newLocation.coordinate.latitude, newLocation.coordinate.longitude)];
[geocodeRequest setDelegate:self];
[geocodeRequest startAsynchronous];
[geocodeRequest release];
[locationManager stopUpdatingLocation];
}
My question is when will the didUpdateToLocation method be called? Only after a new location is found when I perform [locationManager startUpdatingLocation]?
I am facing some weird issue when the user is travelling and on stationary.
Say the user is travelling from point A->B->C->D with 1 min intervals between points. When I call my method at point C, sometime it returns the coordinates of point A, sometimes point B and sometimes C. It's just random.
It's even more weird when I am on stationary. I get different coordinates when I calls showLocation method even though I am hooked up on my house WiFi.
I was thinking of implementing the didUpdateToLocation to get the best result it can within 5secs. If within the 5secs, it finds a particular location of an accuracy I had defined, then use the coordinate. If not, use the best it has found within the 5sec time frame. But as I am new I am not sure how to code something like that. I read up NSTimer and it seems like it might work.
Any advices guys?
Thanks a lot in advance!
One of the reasons you are receiving the location from point A is that CoreLocation is returning the last valid location it had first until it can obtain a more accurate location. When you call [locationManager startUpdatingLocation]; it will return the -didUpdateToLocation over and over until you are statisfied and finally call -stopUpdatingLocation.
I think you just need to allow a bit of time for it to get a better location fix before you stop updating your location. I would consider moving the stop updating location from your -didUpdateToLocation to a different method.
Remove [locationManager stopUpdatingLocation]; from your code and try .
I am totally stumped, here's the situation:
My app uses the Core Location framework to get the current location of the user and then pings my server at TrailBehind for interesting places nearby and displays them as a list. No problems.
To conserve batteries, I turn off the GPS service after I get my data from the server. If the user moves around while using the app and wants a new list he clicks "Refresh" on the navigation controller and the CLLocation service is again activated, a new batch of data is retrieved from the server and the table is redrawn.
While the app is grabbing data from my server I load a loading screen with a spinning globe that says "Loading, please wait" and I hide the navigation bar so they don't hit "back".
So, the initial data grab from the server goes flawlessly.
The FIRST time I hit refresh all the code executes to get a new location, ping the server again for a new list of data and updates the cells. However, instead of loading the table view as it should it restores the navigation controller bar for the table view but still shows my loading view in the main window. This is only true on the device, everything works totally fine in the simulator.
The SECOND time I hit refresh the function works normally.
The THIRD time I hit refresh it fails as above.
The FOURTH time I hit refresh it works normally.
The FIFTH time I hit refresh it fails as above.
etc etc, even refreshes succeed and odd refreshes fail. I stepped over all my code line by line and everything seems to be executing normally. I actually continued stepping over the core instructions and after a huge amount of clicking "step over" I found that the table view DOES actually display on the screen at some point in CFRunLoopRunSpecific, but I then clicked "continue" and my loading view took over the screen.
I am absolutely baffled. Please help!! Many thanks in advance for your insight.
Video of the strange behavior:
Relevant Code:
RootViewControllerMethods (This is the base view for this TableView project)
- (void)viewDidLoad {
//Start the Current Location controller as soon as the program starts. The Controller calls delegate methods
//that will update the list and refresh
[MyCLController sharedInstance].delegate = self;
[[MyCLController sharedInstance].locationManager startUpdatingLocation];
lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil];
[self.navigationController pushViewController:lv animated:YES];
[super viewDidLoad];
}
- (void)updateClicked {
//When the location is successfully updated the UpdateCells method will stop the CL manager from updating, so when we want to update the location
//all we have to do is start it up again. I hope.
[[MyCLController sharedInstance].locationManager startUpdatingLocation];
[self.navigationController pushViewController:lv animated:YES];
//LV is a class object which is of type UIViewController and contains my spinning globe/loading view.
}
-(void)updateCells {
//When the Core Location controller has updated its location it calls this metod. The method sends a request for a JSON dictionary
//to trailbehind and stores the response in the class variable jsonArray. reloadData is then called which causes the table to
//re-initialize the table with the new data in jsonArray and display it on the screen.
[[MyCLController sharedInstance].locationManager stopUpdatingLocation];
if(self.navigationController.visibleViewController != self) {
self.urlString = [NSString stringWithFormat:#"http://www.trailbehind.com/iphone/nodes/%#/%#/2/10",self.lat,self.lon];
NSURL *jsonURL = [NSURL URLWithString:self.urlString];
NSString *jsonData = [[NSString alloc] initWithContentsOfURL:jsonURL];
NSLog(#"JsonData = %# \n", jsonURL);
self.jsonArray = [jsonData JSONValue];
[self.tableView reloadData];
[self.navigationController popToRootViewControllerAnimated:YES];
[jsonData release];
}
}
CLController Methods: Basically just sends all the data straight back to the RootViewController
// Called when the location is updated
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
NSLog(#"New Location: %# \n", newLocation);
NSLog(#"Old Location: %# \n", oldLocation);
#synchronized(self) {
NSNumber *lat = [[[NSNumber alloc] init] autorelease];
NSNumber *lon = [[[NSNumber alloc] init] autorelease];
lat = [NSNumber numberWithFloat:newLocation.coordinate.latitude];
lon = [NSNumber numberWithFloat:newLocation.coordinate.longitude];
[self.delegate noteLat:lat];
[self.delegate noteLon:lon];
[self.delegate noteNewLocation:newLocation];
[self.delegate updateCells];
}
}
The first thought is that you may not want to send startUpdatingLocation to the CLLocationManager until after you've pushed your loading view. Often the first -locationManager:didUpdateToLocation:fromLocation: message will appear instantly with cached GPS data. This only matters if you're acting on every message and not filtering the GPS data as shown in your sample code here. However, this would not cause the situation you've described - it would cause the loading screen to get stuck.
I've experienced similarly weird behavior like this in a different situation where I was trying to pop to the root view controller when switching to a different tab and the call wasn't being made in the correct place. I believe the popToRootViewController was being called twice for me. My suspicion is that your loading view is either being pushed twice or popped twice.
I recommend implementing -viewWillAppear:, -viewDidAppear:, -viewWillDisappear: and -viewDidDisappear: with minimal logging in your LoadingViewController.
- (void)viewWillAppear:(BOOL)animated {
NSLog(#"[%# viewWillAppear:%d]", [self class], animated);
[super viewWillAppear:animated];
}
- (void)viewDidAppear:(BOOL)animated {
NSLog(#"[%# viewDidAppear:%d]", [self class], animated);
[super viewDidAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated {
NSLog(#"[%# viewWillDisappear:%d]", [self class], animated);
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated {
NSLog(#"[%# viewDidDisappear:%d]", [self class], animated);
[super viewDidDisappear:animated];
}
Then, run a test on your device to see if they are always being sent to your view controller and how often. You might add some logging to -updateClicked to reveal double-taps.
Another thought, while your #synchronized block is a good idea, it will only hold off other threads from executing those statements until the first thread exits the block. I suggest moving the -stopUpdatingLocation message to be the first statement inside that #synchronized block. That way, once you decide to act on some new GPS data you immediately tell CLLocationManager to stop sending new data.
Can you try and debug your application to see where the control goes when calling updateCells? Doesn't seem to be anything apparently wrong with the app.
Make sure that there are no memory warnings while you are in the LoadingViewController class. If there is a memory warning and your RootViewController's view is being released, then the viewDidLoad will be called again when you do a pop to RootViewController.
Keep breakpoints in viewDidLoad and updateCells. Are you sure you are not calling LoadingViewController anywhere else?
So, I never did get this to work. I observe this behavior on the device only every time I call popViewController programatically instead of allowing the default back button on the navigation controller to do the popping.
My workaround was to build a custom loading view, and flip the screen to that view every time there would be a delay due to accessing the internet. My method takes a boolean variable of yes or no - yes switches to the loading screen and no switches back to the normal view. Here's the code:
- (void)switchViewsToLoading:(BOOL)loading {
// Start the Animation Block
CGContextRef context = UIGraphicsGetCurrentContext();
[UIView beginAnimations:nil context:context];
[UIView setAnimationTransition: UIViewAnimationTransitionFlipFromLeft forView:self.tableView cache:YES];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationDuration:.75];
// Animations
if(loading) {
if (lv == nil) { lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil]; }
[self.view addSubview:lv.view];
[self.view sendSubviewToBack:self.tableView];
self.title = #"TrailBehind";
}
else {
[lv.view removeFromSuperview];
}
// Commit Animation Block
[UIView commitAnimations];
//It looks kind of dumb to animate the nav bar buttons, so set those here
if(loading) {
self.navigationItem.rightBarButtonItem = nil;
self.navigationItem.leftBarButtonItem = nil;
self.title = #"TrailBehind";
}
else {
UIBarButtonItem *feedback = [[UIBarButtonItem alloc] initWithTitle:#"Feedback" style:UIBarButtonItemStylePlain target:self action:#selector(feedbackClicked)];
self.navigationItem.rightBarButtonItem = feedback;
UIBarButtonItem *update = [[UIBarButtonItem alloc] initWithTitle:#"Move Me" style:UIBarButtonItemStylePlain target:self action:#selector(updateClicked)];
self.navigationItem.leftBarButtonItem = update;
[feedback release];
[update release];
}
}
Looking at your original code, I suspect this block very much:
- (void)viewDidLoad {
...
lv = [[LoadingViewController alloc] initWithNibName:#"Loading" bundle:nil];
[self.navigationController pushViewController:lv animated:YES];
[super viewDidLoad];
}
viewDidLoad is called every time the NIB is loaded, which can happen multiple times, especially if you run low on memory (something that seems likely given your remark that it only happens on device). I recommend that you implement -didReciveMemoryWarning, and after calling super, at the very least print a log so you can see whether it's happening to you.
The thing that bothers me about the code above is that you're almost certainly leaking lv, meaning that there may be an increasing number of LoadingViewControllers running around. You say it's a class variable. Do you really mean it's an instance variable? ivars should always use accessors (self.lv or [self lv] rather than lv). Do not directly assign to them; you will almost always do it wrong (as you are likely dong here).
I came across this while searching for the exact same issue, so while I'm sure you've already solved your problem by now, I figured I'd post my solution in case someone else runs across it...
This error seems to be caused when you assign two IBActions to the same UIButton in interface builder. It turned out that the button I used to push the view controller onto the stack was assigned to two IBActions, and each one was pushing a different controller onto the navigationController's stack (although you'll only end up seeing one of them - perhaps the last one to be called). So anyway, pressing the back button on the topmost view doesn't really dismiss it (or maybe it's dismissing the 2nd, unseen controller), and you have to press twice to get back.
Anyway, check your buttons and be sure they're only assigned to a single IBAction. That fixed it for me.