[iOS]如何动态获取键盘的高度

// 给键盘添加监听事件
[[NSNotificationCenter
defaultCenter] addObserver:self
selector:@selector(myKeyBoardAction:)
name:UIKeyboardDidShowNotification
object:nil];

NSDictionary *dic = [notif
userInfo];
NSValue *value = [dic
objectForKey:UIKeyboardFrameBeginUserInfoKey];
CGSize size = [value
CGRectValue].size;