how to set dynamic height of a Collection View, th

问题:

I have embedded a collection view in another view and disabled the collection view's scrolling ability, what i want to achieve is similar to Instagram's profile tab. However, I cannot figure out how should I set the height of the collection view in this case since the number of cells are dynamic.

I tried searching different solutions but most results are on changing the cells dynamically but not the collection view height itself. Is there any default/standard solutions for that?

回答1:

Set the width you want the collection view to have (hopefully that is static), and request a layout:

collectionView.frame = CGRectMake(0., 0., width, 0.);
[collectionView layoutIfNeeded];

The calculated height of the collectionView will then be available at:

collectionView.contentSize.height

回答2:

For Swift please follow below steps:

Declare a CGFloat variable in declaration section:

var height : CGFloat!

At viewDidAppear you can get it by:

height = self.myCollectionView.collectionViewLayout.collectionViewContentSize().height

Maybe when you reload data then need to calculate a new height with new data then you can get it by: addObserver to listen when your CollectionView finished reload data at viewWillAppear:

override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(true)
        ....
        ....
        self.shapeCollectionView.addObserver(self, forKeyPath: "contentSize", options: NSKeyValueObservingOptions.Old, context: nil)
    }

Then add bellow function to get new height or do anything after collectionview finished reload:

override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        let newHeight : CGFloat = self.myCollectionView.collectionViewLayout.collectionViewContentSize().height

        var frame : CGRect! = self.myCollectionView.frame
        frame.size.height = newHeight

        self.myCollectionView.frame = frame
    }

And don't forget to remove observer:

self.myCollectionView.removeObserver(self, forKeyPath: "contentSize")

I hope this will help you to solve your issue in swift.

回答3:

In your ViewController, set the frame of the collectionView. For example:

    self.collectionView.frame = CGRectMake(0, 0, 100, 200);

回答4:

Based on the fact you know the height of the cells and you know the number of cells on the screen. I would...

self.collectionView.frame = CGRectMake(0, 0, DEFINED_WIDTH, DEFINED_CELL_HEIGHT*Number of Cells);

or have I miss understood the question?