UiScrollView Incorrect Height (Without AutoConstraint) - ios

Question

Searched a lot on stack overflow, but didn't find any solution that works for us.
What we have are a couple of Views and UILabels and UIButtons in UIScrollView as below format. On Click of button we are hiding couple of views and labels and trying to recalculate UIScollView height.
UIScrollView
-->UIView
-->UIView2
-->UIView3
-->UILabel1
-->UILabel2 ( Please note these labels are not inside UIView, they are directly added to scrollview. Is this correct approach or they should be added inside a UIView?)
-->UITextField (Directly added to scrollview)
-->UITextField1 (Directly added to scrollview)
-->UIButton ( On Click of Button above textfields and labels are hidden or shown based on business logic)
When we try to reset size of UIScrollview on UIButton click it doesn't calculate height correctly. Tried below solution shared by lot of answers in stack overflow
Is the problem with labels and buttons added directly to UIScrollView?
Is there better way to set height of UIScrollview correctly?
We don't want to use AutoConstraint
CGRect contentRect = CGRectZero;for (UIView *view in uiScrollViewObj.subviews) {
contentRect = CGRectUnion(contentRect, view.frame);
}
uiScrollViewObj.contentSize = contentRect.size;

Answer 1

No it's not, in fact UILabels and UIButtons are UIViews.
I think you are confusing two concepts. The UIScrollView height is the height of the viewport (the visible part of the scrollview). What you want to change is the contentSize height that is the height of the whole content which you want to scroll through (I don't know if I have explain myself clear).
If the structure is the way you said it, so the UIButton is the closest element to the button, you should move its frame and place it upper, otherwise the contentSize is always gonna be the same.
Besides that, your code is iterating through all the views of the scrollview and those are not only the ones you added but also the ones that Apple inserted.

Answer 2

The best way to calculate the contentsize dynamically is to sum scrollview subviews y position and their height. Something like this should work:
CGFloat viewY, maxY=0;
for (UIView *view in uiScrollViewObj.subviews) {
if (view.hidden) continue;
viewY = view.frame.origin.y + view.frame.size.height;
maxY = (viewY > maxY) ? viewY : maxY;
}
[uiScrollViewObj setContentSize:CGSizeMake(uiScrollViewObj.frame.size.width, maxY)];