iOS获取键盘高度

- (void) registerForKeyboardNotifications{
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showKeyBoard:) name:UIKeyboardDidShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hideKeyBoard:) name:UIKeyboardDidHideNotification object:nil];

}

- (void)showKeyBoard:(NSNotification *) notification{
NSDictionary *info = [notification userInfo];
NSValue *value = [info objectForKey:UIKeyboardBoundsUserInfoKey];
CGSize keyboardSize = [value CGRectValue].size;
CGRect scrollViewFrame= [scrollView frame];
scrollViewFrame.size.height -= keyboardSize.height;
scrollView.frame = scrollViewFrame;
[scrollView scrollRectToVisible:inputElementFrame animated:YES];
isShowKeyboard = YES;
}

- (void)hideKeyBoard:(NSNotification *)notification{
NSDictionary *info = [notification userInfo];
NSValue *value = [info objectForKey:UIKeyboardBoundsUserInfoKey];
CGSize keyboardSize = [value CGRectValue].size;
CGRect scrollViewFrame= [scrollView frame];
scrollViewFrame.size.height += keyboardSize.height;
scrollView.frame = scrollViewFrame;
isShowKeyboard = NO;
}