Is there a way to detect that the extent has changed in an app using the ESRI iOS SDK?

Question

Is there a delegate, callback, or other method that can be used to detect that the extent of the map has been changed in the ESRI iOS SDK?

Answer 1

According to the class reference for AGSMapView, there are two NSNotifications that are broadcast whenever the map pans or zooms to a new extent. Set up a listener for those notifications.

The map component also broadcasts 2 notifications -

AGSMapViewDidEndPanningNotification and #AGSMapViewDidEndZoomingNotification .

Answer 2

As answered already, you can use the 2 notifications: AGSMapViewDidEndPanningNotification and AGSMapViewDidEndZoomingNotification

However, if you need more immediate feedback you can add an observer to the AGSMapVeiw's visibleAreaEnvelope property:

[self.mapView addObserver:self forKeyPath:@"visibleAreaEnvelope" options:NSKeyValueObservingOptionNew context:nil];

Then you can react to that change like so:

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    if (
        [keyPath isEqualToString:@"resolution"] ||
        [keyPath isEqualToString:@"visibleAreaEnvelope"] ||
        [keyPath isEqualToString:@"rotationAngle"] ||
        [keyPath isEqualToString:@"mapScale"]){
        NSLog(@"   ---> %@ changed...", keyPath);
    }
    else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}