customize callout

http://stackoverflow.com/questions/1565828/customize-callout-bubble-for-annotationview http://stackoverflow.com/questions/8018841/customize-the-mkannotationview-callout http://furnacedigital.blogspot.com/2011/08/uicalloutview.html http://furnacedigital.blogspot.com/2011/08/cmpoptipview.html