...或采取简单的方法:

…or take the easy way:

当您输入 textField 时，它会成为第一响应者并出现键盘.您可以使用 [myTextField isFirstResponder] 检查键盘的状态.如果返回YES，则键盘处于活动状态.

When you enter a textField, it becomes first responder and the keyboard appears. You can check the status of the keyboard with [myTextField isFirstResponder]. If it returns YES, then the the keyboard is active.