如何设置对输入字段的关注？

问题：

What is the 'Angular way' to set focus on input field in AngularJS? 在AngularJS中将焦点设置在输入字段上的“角度方式”是什么？

More specific requirements: 更具体的要求：

When a Modal is opened, set focus on a predefined <input> inside this Modal. 打开模态后，将焦点放在此模态内的预定义<input> 。
Everytime <input> becomes visible (eg by clicking some button), set focus on it. 每当<input>变为可见时（例如，通过单击某些按钮），请将焦点设置在它上面。

I tried to achieve the first requirement with autofocus , but this works only when the Modal is opened for the first time, and only in certain browsers (eg in Firefox it doesn't work). 我试图通过autofocus 达到第一个要求，但这仅在首次打开Modal时有效，并且仅在某些浏览器中有效（例如，在Firefox中不起作用）。

Any help will be appreciated. 任何帮助将不胜感激。