将注释删除/添加到mapview会导致内存泄漏

I've been trying to get rid of memory leaks in mapview. I am using custom map pin class. Everything works, but problem is - I need to filter mapview results. when i remove all mapview annotations - and add filtered results - performance tool finds leaks. but in this mapPin class I am using are used autorelease, so they should be released, but they aren't. what am I doing wrong? I've been trying to get rid of memory leaks in