didUpdateLocation Method Never Called

问题:

I am making one app on iphone sdk4.0.In that did update location method never called. I have given my code below.Please help.Thanks in advance.

-(id)init
{
    [super init];

    obj=[[UIApplication sharedApplication]delegate];

    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    //locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
    locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m
    [locationManager startUpdatingLocation];

    return self;

}

-(void)locationManager:(CLLocationManager *)manager
   didUpdateToLocation:(CLLocation *)newLocation
          fromLocation:(CLLocation *)oldLocation
{
    NSLog(@"%f",newLocation.coordinate.latitude);

    NSLog(@"%f",newLocation.coordinate.longitude);

    obj=[[UIApplication sharedApplication]delegate];

    location=[[CLLocation alloc]initWithLatitude:newLocation.coordinate.latitude longitude:newLocation.coordinate.longitude];
    obj.lattitude1=[NSString stringWithFormat:@"%f",newLocation.coordinate.latitude];

    obj.longitude1=[NSString stringWithFormat:@"%f",newLocation.coordinate.longitude];
    //location=[[CLLocation alloc]initWithLatitude:39.9883 longitude:-75.262227];
}

回答1:

HI, your codes seems ok. now these can be possible reasons :

on your init: try to check if there is locationServicesEnabled or not.

locationManager = [[CLLocationManager alloc] init];
if(locationManager.locationServicesEnabled == NO){
    //Your location service is not enabled, Settings>Location Services  
}

other reason, you may disallow to get location to your app. solution: simply remove your application from iPhone and re-build, now it should popup dialog to Allow location.

use this to check error

- (void)locationManager:(CLLocationManager *)manager
       didFailWithError:(NSError *)error
{       
    NSLog(@"Error while getting core location : %@",[error localizedFailureReason]);
    if ([error code] == kCLErrorDenied) {
        //you had denied 
    }
    [manager stopUpdatingLocation];
}

otherwise all seems ok, you were already running ios 4.0 , which can be install in iPhone 3G and later, if it was iPhone 2g, then this problem may occur.

回答2:

Furthermore in iOS8 you must have two extra things:

• Add a key to your Info.plist and request authorization from the location manager asking it to start.

  • NSLocationWhenInUseUsageDescription

  • NSLocationAlwaysUsageDescription

• You need to request authorization for the corresponding location method.

  • [self.locationManager requestWhenInUseAuthorization]

  • [self.locationManager requestAlwaysAuthorization]

Code example:

self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
// Check for iOS 8. Without this guard the code will crash with "unknown selector" on iOS 7.
if ([self.locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)]) {
    [self.locationManager requestWhenInUseAuthorization];
}
[self.locationManager startUpdatingLocation];

Source: http://nevan.net/2014/09/core-location-manager-changes-in-ios-8/

回答3:

Make sure you added CLLocationManager as a property.

@property (nonatomic , strong) CLLocationManager *locationManager;

回答4:

If you are testing this on the simulator it will not work.

This happens because that method is only called when the device changes location (and the simulator never changes location).

回答5:

Does -locationManager:didFailWithError: in your delegate ever get called? Maybe you denied access to location data at some point and now don't get prompted, but access is denied.

回答6:

After you alloc and init your location manager, check to see if location services are allowed. This code is from Apple's "LocateMe" code sample

if (locationManager.locationServicesEnabled == NO) {
    UIAlertView *servicesDisabledAlert = [[UIAlertView alloc] initWithTitle:@"Location Services Disabled" message:@"You currently have all location services for this device disabled. If you proceed, you will be asked to confirm whether location services should be reenabled." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [servicesDisabledAlert show];
    [servicesDisabledAlert release];
}

If you're testing with the simulator, try testing with a device instead. The simulator requires that the computer's WiFi is turned on, and that it can locate a WiFi base station that's in it's database of known locations.