View at the bottom in a UIScrollView, with AutoLayout
Fairly easy to do with Auto-Layout only... no code required.
The key is to use a "content view" to hold the elements, and a greater-than-or-equal
constraint between your "bottom" element and your "footer" view.
In this image, yellow is the main view, green is the scroll view, blue is the content view, the labels are gray and the footer view is pink.
- Start with a fresh view controller
- add a scroll view, normal constraints (I used
20
all the way around, so we can see the frame) - add a
UIView
to the scrollView - this will be our "content view" - constrain contentView Top/Bottom/Leading/Trailing all equal to
0
to the scrollView - constrain both the Width and Height of the contentView equal to the scrollView
- add your elements - here I used 3 labels
- constrain the labels as usual... I used:
- LabelA - Top/Leading/Trailing all at
20
, vertical spacing to LabelB of60
- LabelB - Leading/Trailing at
20
, vertical spacing to LabelC of60
- LabelC - Leading/Trailing at
20
- LabelA - Top/Leading/Trailing all at
- LabelC is also set to
Number of Lines: 0
so it will expand with multiple lines of text - Add a
UIView
as a "footer view" (I stuck a label in it) - constrain the footerView Leading/Trailing/Bottom all at
20
(so we can see the frame) - either set a Height constraint on footerView, or use its content to constrain its height
- add a Vertical Spacing constraint from LabelC to footerView, and set it to
>= 40
- last step, change the Height constraint of contentView to
Priority: 250
Now, as you expand/contract the height of LabelC, the footerView will keep at least 40-pts of vertical space. When LabelC gets big enough to "push" footerView below the bottom, scrollView will become scrollable.
Results:
you need to check ContentSize of scrollView and modify FooterView Top Constraint with the required Value
My class code
import UIKit
class scrollViewDrag: UIViewController
{
/// ScrollView Outlet
@IBOutlet weak var mainScrollView: UIScrollView!
/// Footer View top spacing constraint
@IBOutlet weak var footerViewTopConstraint: NSLayoutConstraint!
/// Used for ScrollView Height
var screenHeight = CGFloat()
/// Did Load
override func viewDidLoad() {
super.viewDidLoad()
}
/// Function used to check for height
func checkForHeight(){
/// Get scrollView Height
screenHeight = mainScrollView.frame.size.height
/// Check contentSize Height ?
if mainScrollView.contentSize.height >= screenHeight {
/// When ScrollView is having height greater than your scrollView Height
/// Footer will scroll along other Views
}
else{
/// Issue Case
let spacingValue = screenHeight-mainScrollView.contentSize.height
footerViewTopConstraint.constant = spacingValue
}
}
/// Call the height function in DidAppear
override func viewDidAppear(_ animated: Bool) {
checkForHeight()
}
}
Storyboard
I had used Four View with Equal Heights And at last a footerView is attached as Fourth View
FooterView Top Constraint
Top constraint used as footerViewTopConstraint
Output
Case 1 - Size is greater than scrollView Height
Case 2 - Expected Output