带有自动布局的ScrollView

Question

I have a weird output with autoLayout used for following scenario.

I have 4 sub pages to scroll. (subPage or scrollPage has been designed separately with autoLayout).

MainView has a scrollView component which loads the sub pages.

Everything is fine except the starting. After first load, the sub page components are not arranged properly. As soon as it receives a first tap/touch, automatically re-scrolls/re-arranges to proper places. which looks like a bug.

The loading creates problem. I have attached 2 images for reference for the above scenarios. FirstOne at the first loading

Second one just after tapping on scroll area

Second one is the proper one. I need to show this instead of the first. Need help to fix this.

Thanks, Satyaranjan

One more thing to note, [myScroll scrollRectToVisible:CGRectMake(320*pageNumber, 0, 320 , 240) animated:NO]; this is not working As I am using dynamic width for the subPage. Because it will vary for iPhon5 and iPhone6

Answer 1

First, you generally don't want to set the scrollView's contentSize when using autolayout -- if your sub views are laid out correctly, it will do that automatically.

Try this:

• constrain all four of scrollView's edges to its parent
• make sure translatesAutoresizingMaskIntoConstraints is NO for all views
• Create a view called "contentView" and parent it to the scrollView.
• pin all four of contentViews's edges to scrollView
• parent your subviews to contentView and arrange them with autolayout

If for some reason you need to change the size of a subview programmaticly, you need to override its intrinsicContentSize method to return the correct size after the change. After the change, you might need to call the view's sizeToFit method from its parent view (not sure about that -- it may happen automatically).

In general, when using autolayout, you should almost never explicitly set the size of anything. If it can't be avoided, you should do it by creating height/width constraints and modifying them at runtime in the updateConstraints method.

EDIT:

I made an example project which demonstrates how to set up a scrollView and a couple other things.

Take a look!

https://github.com/annabd351/AutolayoutTemplate