MKMapView not refreshing annotations - objective-c

Question

I have a MKMapView (obviously), that shows housing locations around the user.
I have a Radius tool that when a selection is made, the annotations should add/remove based on distance around the user.
I have it add/removing fine but for some reason the annotations won't show up until I zoom in or out.
This is the method that adds/removes the annotations based on distance. I have tried two different variations of the method.
Adds the new annotations to an array, then adds to the map by [mapView addAnnotations:NSArray].
Add the annotations as it finds them using [mapView addAnnotation:MKMapAnnotation];
1.
- (void)updateBasedDistance:(NSNumber *)distance {
//Setup increment for HUD animation loading
float hudIncrement = ( 1.0f / [[[[self appDelegate] rssParser]rssItems] count]);
//Remove all the current annotations from the map
[self._mapView removeAnnotations:self._mapView.annotations];
//Hold all the new annotations to add to map
NSMutableArray *tempAnnotations;
/*
I have an array that holds all the annotations on the map becuase
a lot of filtering/searching happens. So for memory reasons it is
more efficient to load annoations once then add/remove as needed.
*/
for (int i = 0; i < [annotations count]; i++) {
//Current annotations location
CLLocation *tempLoc = [[CLLocation alloc] initWithLatitude:[[annotations objectAtIndex:i] coordinate].latitude longitude:[[annotations objectAtIndex:i] coordinate].longitude];
//Distance of current annotaiton from user location converted to miles
CLLocationDistance miles = [self._mapView.userLocation.location distanceFromLocation:tempLoc] * 0.000621371192;
//If distance is less than user selection, add it to the map.
if (miles <= [distance floatValue]){
if (tempAnnotations == nil)
tempAnnotations = [[NSMutableArray alloc] init];
[tempAnnotations addObject:[annotations objectAtIndex:i]];
}
//For some reason, even with ARC, helps a little with memory consumption
tempLoc = nil;
//Update a progress HUD I use.
HUD.progress += hudIncrement;
}
//Add the new annotaitons to the map
if (tempAnnotations != nil)
[self._mapView addAnnotations:tempAnnotations];
}
2.
- (void)updateBasedDistance:(NSNumber *)distance {
//Setup increment for HUD animation loading
float hudIncrement = ( 1.0f / [[[[self appDelegate] rssParser]rssItems] count]);
//Remove all the current annotations from the map
[self._mapView removeAnnotations:self._mapView.annotations];
/*
I have an array that holds all the annotations on the map becuase
a lot of filtering/searching happens. So for memory reasons it is
more efficient to load annoations once then add/remove as needed.
*/
for (int i = 0; i < [annotations count]; i++) {
//Current annotations location
CLLocation *tempLoc = [[CLLocation alloc] initWithLatitude:[[annotations objectAtIndex:i] coordinate].latitude longitude:[[annotations objectAtIndex:i] coordinate].longitude];
//Distance of current annotaiton from user location converted to miles
CLLocationDistance miles = [self._mapView.userLocation.location distanceFromLocation:tempLoc] * 0.000621371192;
//If distance is less than user selection, add it to the map.
if (miles <= [distance floatValue])
[self._mapView addAnnotation:[annotations objectAtIndex:i]];
//For some reason, even with ARC, helps a little with memory consumption
tempLoc = nil;
//Update a progress HUD I use.
HUD.progress += hudIncrement;
}
}
I have also attempted at the end of the above method:
[self._mapView setNeedsDisplay];
[self._mapView setNeedsLayout];
Also, to force a refresh (saw somewhere it might work):
self._mapView.showsUserLocation = NO;
self._mapView.showsUserLocation = YES;
Any help would be very much appreciated and as always, thank you for taking the time to read.

Answer 1

I'm going to guess that updateBasedDistance: gets called from a background thread. Check with NSLog(#"Am I in the UI thread? %d", [NSThread isMainThread]);. If it's 0, then you should move the removeAnnotations: and addAnnotation: to a performSelectorOnMainThread: invocation, or with GCD blocks on the main thread.