How to make UIScrollView height equal to content height? - ios

Question

I have an UIScrollView and horizontally scrollable content. I can properly set up the content size, etc, but I need to place another similar ScrollView just below the first one. So, I need to make height of the ScrollView to be equal to height of its content. Currently I use this code, but it does not work. I attached screenshot with issue and the code:
//setting the correct content size of scrollView (self.contentSize is already calculated)
self.imageScrollView.contentSize = self.contentSize;
//creating temporary CGRect
CGRect frame = self.imageScrollView.frame;
//Changing the height and re-assigning new frame to imageScrollView
frame.size.height = self.contentSize.height;
self.imageScrollView.frame = frame;
Look at the screenshot: the imageScrollView is just below NavBar. The content still scrollable and the size of ScrollView is smaller than content size.

Answer 1

You can't set the frame's height using frame.size.height = self.contentSize.height;
Instead use frame = CGRectMake(x, y, width, height); Ex:
self.imageScrollView.frame = CGRectMake(self.imageScrollView.frame.origin.x, self.imageScrollView.frame.origin.y, self.imageScrollView.frame.size.width, self.contentSize.height);
And from the looks of things, I suspect the content size of your imageScrollView is correct, but it's being hidden by your nav bar. In which case, I recommend setting imageScrollView frame's origin to the height of the nav bar, ex:
self.imageScrollView.frame = CGRectMake(self.imageScrollView.frame.origin.x, self.navigationController.navigationBar.frame.size.height, self.imageScrollView.frame.size.width, self.contentSize.height);
Update #1: Here's a link to a great answer explaining why you can't set the frame in the way you've attempted: ios frame change one property (eg width)
So basically you can edit a lone CGRect structure by changing a single property, but you can NOT update a CGRect in that way if it's a property of another object -- in this case a property of a frame.
Update #2: Also, to change the position of elements in your interface, place the code in viewDidLayoutSubviews, not in viewDidLoad.
Update #3: To have the code in viewDidLayoutSubviews only processed once, enclose it in a conditional, ex:
bool subviewsLaidout;
- (void)viewDidLoad {
subviewsLaidout = NO;
}
- (void)viewDidLayoutSubviews {
if (!subviewsLaidout) {
self.imageScrollView.frame = CGRectMake(self.imageScrollView.frame.origin.x, self.navigationController.navigationBar.frame.size.height, self.imageScrollView.frame.size.width, self.contentSize.height);
subviewsLaidout = YES;
}
}