问题描述

我正在开发一个支持纵向和横向模式的应用程序.我正在使用 auto layout 来安排我的视图.由于我阅读了很多帖子，并且我意识到开发人员通常使用以下方法之一.

I am developing an application which supports portrait and landscape modes. I am using auto layout to arrange my views. As i have been reading many posts and i have realized that developers commonly use one among the following approaches.

1.第一种方法:

实现UIViewController:updateConstraints方法，根据设备方向更新约束.

Implement the UIViewController:updateConstraints method and update constraints according to device orientation.

<强>2.第二种方法:

实现UIViewController:viewWillLayoutSubviews方法，根据设备方向更新约束.

Implement the UIViewController:viewWillLayoutSubviews method and update constraints according to device orientation.

谁能告诉我最好的使用方法是什么?我一直在寻找结合自动旋转和自动布局的最佳实践，但还没有.谢谢.

Could anyone please tell me what is the best approach to use ? I have been searching for a best practice to combine autorotation and auto layout and nothing yet. Thanks.

推荐答案

我会使用这个 UIViewController 的方法:

I would use this UIViewController's method:

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation 持续时间:(NSTimeInterval)duration;

在旋转时调用，并从那里调用 -setNeedsUpdateConstraints.如果您需要进行额外的计算或管理约束添加

that is called upon rotation, and call -setNeedsUpdateConstraints from there. If you need to do additional calculations or manage the contrainsts add

- (void)updateViewConstraints
{
    [super updateViewConstraints];
    // do calculations if needed, like set constants
}

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