UIScrollView scrolls horizontally instead of vertically?

Question

I have a UIScrollView with a textfield and a UIImageView in it. I'm trying to make it scroll vertically (with support for device rotation to landscape v. portrait) but no matter what I do, it only scrolls horizontally instead of vertically and I have no idea why.

I have read a lot about autolayout and scrollview so I thought it might be an autolayout issue. However, I have already configured the autolayout to handle the rotation switch to landscape so I'd like to keep it on. The subviews are added through the storyboard to the scrollview.

I'm also in general confused about contentSize of the scrollView. Should this be larger than the screen size like in the documentation? I also saw a stackoverflow question in which it was supposed to be the same size as the screen which confused me.

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self.scrollView setDelegate:self];
    self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height+400);
}

-(void)orientationChanged:(NSNotification *)notification{
    self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height+400);

}

just for the debugging cause, can you measure the scrollview frame ? just hardcode self.scrollView.frame = CGRectMake(0,0,320,480) and see if you get the same behavior. — yunas

Alfie Hanssen Alfie Hanssen · Accepted Answer · 2013-07-29T18:38:10

The scrollView's scroll direction will be determined by the contentSize's relation to the scrollView's frame. The contentSize is the size of the container that holds all of the scrollView's subviews (the container that the scrollView is effectively a window into).

First, set the scrollView.frame to whatever you want it to be.

Second, add your image (or whatever other content) to the scrollView. Make sure the image height is <= the scrollView.frame.size.height to ensure horizontal scrolling only. (As far as I know there's no directionLock for UIScrollView.) ContentSize should be set automatically but you can also set it directly, something like:

[scrollView setContentSize:(CGSize){scrollView.size.height, someLargeWidth}];

You should not need to re-set the contentSize upon rotation. You can either set the scrollView.frame explicitly on rotation, or use autoresizingMask or use autoLayout.

UIScrollView scrolls horizontally instead of vertically?

1 Answers