It adds the controller's view as a subview of the window.

它创建了一个视图控制对象用来管理窗口视图对象的内容。

youdao

One way I can do is to set the leading space and trailing space of the top subview with respect to the main view and also centering horizontally in the main view.

我可以做的一个方法是设置顶部子视图相对于主视图的前导空格和尾随空格，并且在主视图中水平居中。

youdao

One way I can do is to set the leading space and trailing space of the top subview with respect to the main view and also centering horizontally in the main view.

我可以做的一个方法是设置顶部子视图相对于主视图的前导空格和尾随空格，并且在主视图中水平居中。

youdao