I have problem with button click. I put a button in a view which is put in a view controller in a navigation controller stack. it is a little complex. but the problem is weird. when I click the top of the button, the action of the button can be triggered. but when I click the bottom, the action is not called at all. does anyone have the same problem here? it looks like a bug of ipad simulator. my application is an ipad app and now no device to test it.