Why does Apple use assign rather than weak to stor

Question

Some Cocoa and Cocoa Touch classes declare their delegate properties as assign rather than weak, which forces users of the class to nil out the property in dealloc

-(void)dealloc
{
    self.imageScrollView.delegate = nil;
    self.tableView.delegate = nil;
    self.tableView.dataSource = nil;
}

Which is very cumbersome.

Why would Apple do it this way?

Answer 1

The reason why is that not all system classes have been compiled with ARC.

You may implement a dealloc method if you need to manage resources other than releasing instance variables. You do not have to (indeed you cannot) release instance variables, but you may need to invoke [systemClassInstance setDelegate:nil] on system classes and other code that isn’t compiled using ARC.

See this page on developer.apple.com: Transitioning to ARC Release Notes