Iphone – Problem with UIScrollView Content Offset

ipadiphoneuiscrollview

Im developing an iPad app in which I have a scrollview, the size of which i determine dynamically depending on the number of objects i display in it. Now, though i have not set any content offset I find that the scroll view has been offset by some amount whenever the view loads. When I check the value of the offset, it shows 0. I dont understand why without having a contentOffset value, the scrollview behaves that way. Any reasons for this?

I suspect this has something to do with iOS 4.2 as i dont remember this problem occurring when i was testing the app on iOS 3.2.

Update: The amount its getting offset seems to vary based on the contentSize of the scrollView. If the contentSize of the scrollView matches that of its frame height (its a vertical scrollview), then there is no offset. As the contentSize increases above the value of the height of the scrollView frame, the offset also increases proportionally. However, scrollView.contentOffset.y still = 0.0

Best Answer

if u use interface builder -

add scrollview to the view
create another view and add elements that u need to add to scroll view

then add this second view to scrollview

write this code in Viewdidload scrollview.contentsize.y = lastelement.frame.origin.y + lastelement.frame.size.height + 10

this will adjust the scrollview to content size. it displays the first element and can scroll from top to bottom.

Related Solutions

Iphone – UIScrollView works as expected but scrollRectToVisible: does nothing

Over a month later, and I finally figured it out. While the alternative above worked well, it has been bugging me and I had to finally figure it out. Turns out that it was somewhat of a stupid mistake.

Here's the old code in my viewDidLoad, where I set up the scrollView:

[clefScrollView setContentSize:CGSizeMake(clefScrollView.contentSize.width, clefView.frame.size.height)];

The value of a scrollView height or width can't be 0! I think this got past me because I was assuming that ScrollView sizes start out with a valid size, and I was missing the fact that one dimension was zero!

This works:

[clefScrollView setContentSize:CGSizeMake(clefView.frame.size.width, clefView.frame.size.height)];

Hope this helps someone out there. I definitely spent way too much time trying to debug this.

Ios – UIScrollview content size when orientation changes

Don't use UIDeviceOrientation. Use UIInterfaceOrientation instead. DeviceOrientation has two extra options you don't need here. (UIDeviceOrientationFaceUp and UIDeviceOrientationFaceDown)
Return Yes from shouldAutorotateToInterfaceOrientation
Now willRotateToInterfaceOrientation: duration: will be called every time you rotate your device.

Implement this method like this.

-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
CGRect frame;
int pageNumber = 2;
int statusBarHeight = 20;

if ((toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft) || (toInterfaceOrientation == UIInterfaceOrientationLandscapeRight)) {
    frame = CGRectMake(0, 0, 480, 320 - statusBarHeight);
} else {
    frame = CGRectMake(0, 0, 320, 480 - statusBarHeight);
}

scrollView.frame = frame;
scrollView.contentSize = CGSizeMake(frame.size.width * 2, frame.size.height);
}

Let,

pageNumber = 2

statusBarHeight = 20

Best Answer

Related Solutions

Iphone – UIScrollView works as expected but scrollRectToVisible: does nothing

Ios – UIScrollview content size when orientation changes

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