用通知:
NSNotificationCenter *defaultCenter = [NSNotificationCenter defaultCenter]; [defaultCenter addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil]; [defaultCenter addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil]; [defaultCenter addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil]; [defaultCenter addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];