Filter array based on coordinate from mapview frame in objective C

Question

I have hundred's of map annotation. Annotation are from array of dictionary with lat and long val same data shown in table view. Table view and map view are same view based on screenheight/2. What I need for example in my array have 100 lat and long value table view and mapview show 100 data. If mapview zoomIn then table data(I have no idea how to filter that data) show based on how many annotation show in mapview as same as zoomOut.

What I thought to get that using map view frame size and than convert that into lat and long value and filter array based on lat and long value what I get.

How to convert mapview frame to lat and long value by This answer

Now I don't know what to do. How to filter data with lat and long value.

Is any way to find that or how to arithmetic calculation based lat and long

Answer 1

What you could do is:

A) get the annotations directly:

MKMapRect visibleMapRect = mapView.visibleMapRect;
NSSet *visibleAnnotations = [mapView annotationsInMapRect:visibleMapRect];

B) Loop through your array and check whether the point is inside:

MKMapRect mapRect = mapView.visibleMapRect;
for (NSDictionary *item in array)
{
    CLLocation *location = item[@"location"]; // Or what ever you store...
    MKMapPoint mapPoint = 
    MKMapPointForCoordinate(location.coordinate);
    BOOL inside = MKMapRectContainsPoint(mapRect, mapPoint);
}