CollectionView background clearColor not working

Question

I'm developing a small collectionview 'framework' to behave like a browser tab bar (think chrome) on the iPad. The code is all done, custom flow layout, reordering, and so on and is organized as so :

• TabBarCollectionViewController .h/.m/.xib contains the high logic of the collection view (delegates + datasource methods). I have the xib to configure the collectionView settings and set the custom flow layout (I could do this programmatically, but oh well it's easier that way).

• CustomFlowLayout .h/.m (subclass of flow layout)

• TabBarCell .h/.m/.xib (subclass of collectionviewcell)

Then I'm adding the TabBarCVC as a childViewController on my main viewController (this viewController has many childViewController and subviews) and then as a subview. At this point all is working fiiiiine.

Now the problem, it's so stupid i can't believe i haven't found a way to do this, the backgroundColor of the collectionView is not settable to clearColor. I can put it in gray or whatever color, but that it doesn't support transparency. The cell background color is also clear and does work.

I need the collectionView to be transparent to show the texture on the main view behind. Any insight would be much appreciated, or perhaps i'll fill my first radar to apple.

If i can't find any solution i'll just add the 'screenshot' of the texture supposed to be behind the collectionView and add it as a imageView in the collectionView's backgroundView.

Answer 1

Ok so i'm feeling pretty stupid now. I left an empty UIView behind, acting as a container for the collectionView for a test. I simply forgot to remove it, all is working fine with a nice clearColor now...

Answer 2

In my case I had the background color in the storyboard set to Default. This caused it to have a black background. Changing it to Clear Color worked.

Answer 3

Try setting the color to clear and the background view to an empty view like so...

self.collectionView.backgroundColor = [UIColor clearColor];
self.collectionView.backgroundView = [[UIView alloc] initWithFrame:CGRectZero];

Answer 4

Watch out when setting UICollectionViews Background Color in Storyboard:

The initially selected value Default is Black (counterintuitively).
You have to explicitly select Clear Color for the View to be transparent.

Also note that the Preview in Storyboard immediately changes when this is done 'right'...

Answer 5

The easiest solution is just pick anything color in color picker to change collectionview background then turn the opacity to 0%.

Answer 6

I solved it using in Swift 3:

collectionViewVideo.backgroundColor = UIColor.clear.withAlphaComponent(0)

Answer 7

Fogmeister's answer worked great. Adapted to Swift 3, it would be:

self.collectionView.backgroundColors = [NSColor.clear]
self.collectionView.backgroundView = NSView.init(frame: CGRect.zero)

Answer 8

Swift 4.0 from Fogmeister's answer

self.collectionView.backgroundColor = UIColor.clear
self.collectionView.backgroundView = UIView.init(frame: CGRect.zero)

Answer 9

To have a nice semi-transparent white background use:

collectionView.backgroundColor = UIColor(displayP3Red: 1.0, green: 1.0, blue: 1.0, alpha: 0.35)

Answer 10

In swift this work with me:

self.collectionView.backgroundColor = UIColor(red: 1, green: 1, blue: 1, alpha: 0.0)

Answer 11

What is did to fix it

From Storyboard set collection view background colour as clear colour

then set main view colour to any colour you want , (I set to white.)