How to set different pictures on different pins on map by using MapKit in Objective-C

How to set different image in all pin by using Mapkit and without using the delegate? I used below code, but it's not showing the image on the pin. Please suggest a proper method. Doesn't matter if you suggest a delegate method but it may work properly.

coordinateArray[0].latitude = [[starting_stop_latitude] doubleValue];
coordinateArray[0].longitude = [[starting_stop_longitude] doubleValue];

schoolPin.coordinate = coordinateArray[0];
schoolPin.title = @"School";

[mainMapview addAnnotation:schoolPin];
[[mainMapview viewForAnnotation:schoolPin] setImage:[UIImage imageNamed:@"school_pin"]];
[[mainMapview viewForAnnotation:schoolPin] setCanShowCallout:YES];

coordinateArray[1] .latitude = [[end_stop_latitude] doubleValue];;
coordinateArray[1] .longitude =[[end_stop_longitude] doubleValue];;

homePin.coordinate = coordinateArray[1];
homePin.title = @"Home";

[mainMapview addAnnotation:homePin];
[[mainMapview viewForAnnotation:homePin] setImage:[UIImage imageNamed:@"home_pin"]];
[[mainMapview viewForAnnotation:homePin] setCanShowCallout:YES];