Improved thread-mgmt to prevent crashes

src/ios/CDVBackgroundGeoLocation.h

 //
-//  CDVBackgroundGeoLocation.hs
+//  CDVBackgroundGeoLocation.h
 //
 //  Created by Chris Scott <chris@transistorsoft.com>
 //

src/ios/CDVBackgroundGeoLocation.m

@@ -170,7 +170,18 @@
     // old, too close to the previous one, too inaccurate and so forth according to your own
     // application design.
     [locationCache addObjectsFromArray:locations];
+    
+    UIApplication *app = [UIApplication sharedApplication];
+    
+    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [self stopBackgroundTask];
+        });
+    }];
+    
+    [self.commandDelegate runInBackground:^{
         [self sync];
+    }];
 }
 /**
  * We are running in the background if this is being executed.
@@ -179,15 +190,6 @@
  */
 -(void) sync
 {
-    NSLog(@"- CDVBackgroundGeoLocation sync");
-    
-    UIApplication *app = [UIApplication sharedApplication];
-    
-    // Inform javascript a background-fetch event has occurred.
-    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
-        [self stopBackgroundTask];
-    }];
-    
     // Fetch last recorded location
     CLLocation *location = [locationCache lastObject];
 
@@ -202,14 +204,6 @@
     [returnInfo setObject:[NSNumber numberWithDouble:location.coordinate.latitude] forKey:@"latitude"];
     [returnInfo setObject:[NSNumber numberWithDouble:location.coordinate.longitude] forKey:@"longitude"];
     
-    // Set a timer to ensure our bgTask is murdered 1s before our remaining time expires.
-    backgroundTimer = [NSTimer scheduledTimerWithTimeInterval:app.backgroundTimeRemaining-1
-                                                       target:self
-                                                     selector:@selector(onTimeExpired:)
-                                                     userInfo:nil
-                                                      repeats:NO];
-    
-    [self.commandDelegate runInBackground:^{
     // Build a resultset for javascript callback.
     CDVPluginResult* result = nil;
     
@@ -217,23 +211,14 @@
     [result setKeepCallbackAsBool:YES];
 
     [self.commandDelegate sendPluginResult:result callbackId:syncCallbackId];
-    }];
-}
-- (void)onTimeExpired:(NSTimer *)timer
-{
-    NSLog(@"- CDVBackgroundGeoLocation TIME EXPIRED");
-    [self stopBackgroundTask];
 }
 - (void) stopBackgroundTask
 {
-    [backgroundTimer invalidate];
-    backgroundTimer = nil;
-    
     UIApplication *app = [UIApplication sharedApplication];
     NSLog(@"- CDVBackgroundGeoLocation stopBackgroundTask (remaining t: %f)", app.backgroundTimeRemaining);
     if (bgTask != UIBackgroundTaskInvalid)
     {
-        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
+        [app endBackgroundTask:bgTask];
         bgTask = UIBackgroundTaskInvalid;
     }
 }