CLGeocoder "Lost connection to geod" #error# when use geocodeAddressString:completionHandler

I got this warning when I tried to get destination using CLGeoCoder and the warning is coming out from this method

-(void)geocodeAddressString:(NSString*)addressStringcompletionHandler:(CLGeocodeCompletionHandler)completionHandler;?

when will this issue come out?I will tell you the my experience:

In my app,when I set the CLGeocoder as a @property,or set like this,

CLGeocoder*_geocoder;

when I set app in the background for a moment or a long time, Xcode will log this warning ,and the method will be not available: im getting this issue when am only getting the position on the map.

Lostconnectiontogeod

so I try to quit to set CLGeocoder as a @property,nor set like this,

CLGeocoder*_geocoder

ever time when I use it ,I will init CLGeocoder,like this:

? ? CLGeocoder*gc=[[[CLGeocoderalloc]init]autorelease];

? ? [gcreverseGeocodeLocation:locationObjectcompletionHandler:^(NSArray*placemark,NSError*error){

? ? CLPlacemark*pm=[placemarkobjectAtIndex:0];

? ? NSDictionary*address=pm.addressDictionary;

? ? // do something with the address, see keys in the remark below

? ? }];