Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
422 views
in Technique[技术] by (71.8m points)

objective c - iOS change auto layout constraints when device rotates

I want to modify the layout constraints when the device rotates. My UIViewController is composed of 2 UIViews, in landscape they are horizontally aligned, and in portrait they are vertically aligned.

It does work actually, in willAnimateRotationToInterfaceOrientation, I remove the desired constraints and replaced them with others to have the right layout...

But there are problems, during rotation auto layout starts breaking constraints before willAnimateRotationToInterfaceOrientation is called, so where are we meant to replace our constraints when the device reorientation occurs ?

Another issue is performance, after a few rotations the system doesn't break anymore constraints, but I have a huge performance drop, especially in portrait mode...

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

In willRotateToInterfaceOrientation:duration:, send setNeedsUpdateConstraints to any view that needs its constraints modified.

Alternatively, make a UIView subclass. In your subclass, register to receive UIApplicationWillChangeStatusBarOrientationNotification. When you receive the notification, send yourself setNeedsUpdateConstraints.

This sets the needsUpdateConstraints flag on the view. Before the system performs layout (by sending layoutSubviews messages), it sends an updateConstraints message to any view that has the needsUpdateConstraints flag set. This is where you should modify your constraints. Make a UIView subclass and override updateConstraints to update your constraints.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...