# Register callbacks on this switch to be relayed to `sender`
	private fun set_callback(sender: View)
	import View.on_ios_event in "ObjC" `{

		NitCallbackReference *ncr = [[NitCallbackReference alloc] init];
		ncr.nit_view = sender;

		// Pin the objects in both Objective-C and Nit GC
		View_incr_ref(sender);
		ncr = (__bridge NitCallbackReference*)CFBridgingRetain(ncr);

		[self addTarget:ncr action:@selector(nitOnEvent:)
			forControlEvents:UIControlEventValueChanged];
	`}