How to adjust height of UICollectionView to be the height of the content size of the UICollectionView?

I would suggest the following:

  1. Add a height constraint to your collection view.
  2. Set its priority to 999.
  3. Set its constant to any value that makes it reasonably visible on the storyboard.
  4. Change the bottom equal constraint of the collection view to greater or equal.
  5. Connect the height constraint to an outlet.
  6. Every time you reload the data on the collection view do the following:

Code Sample:

CGFloat height = myCollectionView.collectionViewLayout.collectionViewContentSize.height
heightConstraint.constant = height
self.view.setNeedsLayout() Or self.view.layoutIfNeeded()

Explanation: Extra, You don't have to read if you understand it. obviously!!

The UI will try to reflect all the constraints no matter what are their priorities. Since the height constraint has lower priority of (999), and a bottom constraint of type greater or equal. whenever, the height constraint constant is set to a value less than the parent view height the collection view will be equal to the given height, achieving both constraints.

But, when the height constraint constant set to a value more than the parent view height both constraints can't be achieved. Therefore, only the constraint with the higher priority will be achieved which is the greater or equal bottom constraint.

The following is just a guess from an experience. So, it achieves one constrant. But, it also tries to make the error in the resulted UI for the other un-achieved lower priority constraint as lowest as possible. Therefore, the collection view height will be equal to the parent view size.

d4Rk

I ended up, by subclassing the UICollectionView and overriding some methods as follows.

  • Returning self.collectionViewLayout.collectionViewContentSize for intrinsicContentSize makes sure, to always have the correct size
  • Then just call it whenever it might change (like on reloadData)

Code:

override func reloadData() {
    super.reloadData()
    self.invalidateIntrinsicContentSize()
}

override var intrinsicContentSize: CGSize {
    return self.collectionViewLayout.collectionViewContentSize
}

But be aware, that you lose "cell re-using", if you display large sets of data, eventhough they don't fit on the screen.

You have to set height constraint as equal to content size

HeightConstraint.constant = collection.contentSize.height 

1) Set Fix Height of your CollectionView.

2) Create Outlet of this CollectionView Height Constant. Like :

IBOutlet NSLayoutConstraint *constHeight;

3) Add below method in your .m file:

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];

    CGFloat height = collectionMenu.collectionViewLayout.collectionViewContentSize.height;
    constHeight.constant = height;
}
parthiban

Do following.

  1. first set height constrain for UICollectionView
  2. here calendarBaseViewHeight is UICollectionView height Variable
  3. call the function after reload the collection view

    func resizeCollectionViewSize(){  
           calendarBaseViewHeight.constant = collectionView.contentSize.height      
     }
    

first of all calculate number of cells than multiply it with height of cell and then return height in this method

    collectionView.frame = CGRectMake (x,y,w,collectionView.collectionViewLayout.collectionViewContentSize.height); //objective c
    //[collectionView reloadData];
   collectionView.frame = CGRect(x: 0, y: 0, width: width, height: collectionView.collectionViewLayout.collectionViewContentSize.height) // swift

In Swift 5 and Xcode 10.2.1

1) Fix Height of the CollectionView

2) Create Outlet of your CollectionView

IBOutlet weak var myCollectionViewHeight: NSLayoutConstraint!

3) Use below code

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    let height = myCollectionView.collectionViewLayout.collectionViewContentSize.height
    myCollectionViewHeight.constant = height
    self.view.layoutIfNeeded()
}

On your UICollectionView set your constraints such as Trailing, Leading, and Bottom:

UICollectionView constraints

If you look at my height constraint in more detail, as it is purely for storyboard look so I don't get errors, I have it to Remove at build time. The real height constraint is set in my code down below.

UICollectionView height constraint

My code for DrawerCollectionView, which is set as the collection view Custom Class:

UICollectionView custom class

import UIKit

class DrawerCollectionView: UICollectionView {

    override func didMoveToSuperview() {
        super.didMoveToSuperview()

        heightAnchor.constraint(equalToConstant: contentSize.height).isActive = true
    }
}

work for me

    let heightRes = resCollectionView.collectionViewLayout.collectionViewContentSize.height
    foodHeightConstrant.constant = height.advanced(by: 1 )

    foodCollectionView.setNeedsLayout()
    foodCollectionView.layoutIfNeeded()

Took the solution by d4Rk which is great, except in my case it would keep cutting off the bottom of my collection view (too short). I figured out this was because intrinsic content size was sometimes 0 and this would throw off the calculations. IDK. All I know is this fixed it.

import UIKit

class SelfSizedCollectionView: UICollectionView {
    override func reloadData() {
        super.reloadData()
        self.invalidateIntrinsicContentSize()
    }

    override var intrinsicContentSize: CGSize {
        let s = self.collectionViewLayout.collectionViewContentSize
        return CGSize(width: max(s.width, 1), height: max(s.height,1))
    }

}