在将UICollectionView的数据添加到屏幕之前，先对其进行加载

Question

I have a situation where I need to have a UICollectionView have its data loaded (so I can fetch its content size) before it's been added to the view hierarchy.

I have tried calling reloadData and dispatching on the main_thread but to no avail

 //The context manager needs to check with this to see if the scrollview can scroll (because otherwise it can't pan it up)
    func hasEnoughContentForScrolling()->Bool
    {
        dispatch_sync(dispatch_get_main_queue(), {self.collectionView.reloadData()})

        if(collectionView.contentSize.height > UIScreen.mainScreen().bounds.height)
        {
            return true
        }
        return false
    }

Do you know how I can pre-load a UICollectionView before it's been added to the screen?

Answer 1

You can hide your collectionView in your viewDidLoad method and as collectionView is reloaded you can show your collection View with loaded data. I tried to write the code in Swift. not sure it is the right code for a swift. but may be it can help you to understand-

override func viewDidLoad() 
{super.viewDidLoad()self.collectionView.hidden = YES}  

func hasEnoughContentForScrolling()->Bool   
{ 
   dispatch_sync(dispatch_get_main_queue(),{
   self.collectionView.reloadData()self.collectionView.hidden = NO })
}