CODEWITHSUNDEEP
ioscocoa-touchuiviewcontrolleruiscrollviewautolayout
Ben Packard
Ben Packard

Reputation: 26476

How to scroll a UIScrollView on load when using auto layout

I have a UIScrollView that is set up in the viewDidLoad method of a UIViewController (I'll call it a ScrollViewController). The scroll view contains pages of horizontal content (similar to the native weather app).

When displaying the scrollview, it should be possible to choose which page it starts on. My pattern is this:

The scrolling implementation seems fine, since I am using the same code elsewhere to jump to certain pages. But on first load, nothing happens (that is, the scroll view is not scrolled to the desired page).

I think I have found the reason - it seems that the contentSize of the scroll view (which is derived by autolayout remember) is 0 during viewDidLoad, and this seems that this prevents scrolling. It is also zero during viewWillAppear. Only in viewDidAppear does the scroll work, which of course makes for an odd user experience.

How can I resolve this? Is it wise to somehow force a layout in viewDidLoad? Or some other approach?

Upvotes: 5

Views: 1426

Answers (2)

Yunus Nedim Mehel
Yunus Nedim Mehel

Reputation: 12369

You should be able to set content size manually. Where do you insert the pages inside the scroll view? I would suggest inserting them inside viewDidLoad or viewWillAppear and then scrolling to the desired page just after inserting them by setting its contentOffset.

Upvotes: 0

Lucas Eduardo
Lucas Eduardo

Reputation: 11675

viewDidLayoutSubviews is what you are looking for. This is the method where all the subviews frames are completly initialized. So, try to call your scrollView's setup method inside it, in your viewController:

-(void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    [self setupView];
}

Upvotes: 8

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