Question

Basically, I have a database of locations for an MKMapView, and when the detail disclosure button on each annotation is tapped, it brings up more information on the location, for example their website and phone number.

Problem is, in my database some coordinates only have 4 or 5 decimal points instead of 6, so when the button was tapped the app would crash.
To stop this I added in the UIAlertView to say “We are unable to locate more information”
Is there any way to use my predicate in a better way?

NSString *lat = [NSString stringWithFormat:@"%.6f", view.annotation.coordinate.latitude];
NSString *lon = [NSString stringWithFormat:@"%.6f", view.annotation.coordinate.longitude];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Stores" inManagedObjectContext:_managedObjectContext];
[request setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Latitude == %@ && Longitude == %@", lat, lon];
[request setPredicate:predicate];

NSError *error = nil;
NSArray *stores = [_managedObjectContext executeFetchRequest:request error:&error];
[request release];
if (![stores count]) {
    UIAlertView *alert = [[[UIAlertView alloc]initWithTitle:@"Error" message:@"Sorry, we are unable to locate more information for this location." delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles: nil]autorelease];
    [alert show];
 } else {



    Stores *currentStore = [stores objectAtIndex:0];
    NSLog(@"current store %@", currentStore);

    AddressAnnotation *annotation = view.annotation;

    MoreInfoTable *moreInfoView = [[MoreInfoTable alloc] initWithStyle:UITableViewStyleGrouped];
    moreInfoView.currentStore = currentStore;
    moreInfoView.managedObjectContext = self.managedObjectContext;
    moreInfoView.title = annotation.title ;
    moreInfoView.getWebsite =[NSURL URLWithString:annotation.website];
    moreInfoView.getDirections = [NSURL URLWithString:[NSString stringWithFormat:@"http://maps.google.com/maps?saddr=%f,%f&daddr=%f,%f", mapView.userLocation.coordinate.latitude, mapView.userLocation.coordinate.longitude, annotation.coordinate.latitude, annotation.coordinate.longitude]];
    moreInfoView.footer = [NSString stringWithFormat:@"%.1f miles away", annotation.distanceFromLocation];
    moreInfoView.address = annotation.address;
    moreInfoView.getPhoneNumber = [NSMutableString stringWithString:annotation.phoneNumber];
    moreInfoView.lat = view.annotation.coordinate.latitude;
    moreInfoView.lon = view.annotation.coordinate.longitude;

    [self.navigationController pushViewController:moreInfoView animated:YES];
    [moreInfoView release]; 

}

}

Answer 1

I’m assuming you are trying to get all Stores entities which have a lat or lon. You should check Latitude or Longitude != nil instead of comparing to your 6 decimal string.

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Latitude != nil && Longitude != nil"];
[request setPredicate:predicate];