What can be the reason of memory leaks that originating when I push back to previous view (Navigation Based Application)?

Edited: code added
- (void)viewDidUnload
{
[self setTableView:nil];
[super viewDidUnload];
[self setSearchController:nil];
[self setSearchBar:nil];
toolBar=nil;
}
- (void)dealloc
{
[tableView release];
[searchBar release];
[_toolBar release];
[nominalsArr release];
[searchController release];
[filteredItems release];
[super dealloc];
}
Another edit

By your last image what’s happening is:
you are allocing and then autoreleasing a NSString
then you are assigning it to a retain property, that guess what, retains it (retain count +1)
then you are not releasing it and appparently can’t access it anymore (leaked)