如何在UITextfield数据为空或填充时禁用/启用按钮？

Here is my function. As you can see above, I am able to receive a message in the console when the text field is empty (or nil), and the button is disabled. However, when data is entered into my text field, I am not getting a response. Much appreciation if someone can help me with a solution for this or an analogous one.Here is my function. As you can see above, I