[iOS] 更新地標後，調整地圖適當大小！

Under iOS 4.2.1, the mapView:didAddAnnotationViews: method is not being called when the user's location is updated

改用 (void)mapView:(MKMapView *)mv didUpdateUserLocation:(MKUserLocation *)userLocation

所以要在更新 user 位置後調整地圖至適當的大小：

- (void)mapView:(MKMapView *)mv didUpdateUserLocation:(MKUserLocation *)userLocation {
    MKCoordinateRegion region = 
        MKCoordinateRegionMakeWithDistance([userLocation coordinate], 250, 250);
    
[mv setRegion:region animated:YES];
}

參考 forums.bignerdranch.com • View topic - Whereami under iOS 4.2.1

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