UICollectionView重载数据在swift 4中不起作用

Question

I migrated my ios app code to Swift 4 and reload data method in my collection views doesn't work. I searched and try a lot of things but no one worked. It was working perfectly for more than a month in Swift 3, so I don't know what is happening.

This code is for one of the cases:

private func setLevelLessons(){
        let operationsDB = DBOperations()
        self.indexInformation = operationsDB.getIndex(forLevel: self.currentLevel)
        self.numLessons = (self.indexInformation?.count)!
        DispatchQueue.main.async {
            self.lessonsCollectionView.reloadData()
        }
    }

I call this function when a button is clicked. When is clicked I get data from database and reload collection view. I checked if data is correct so that's not the problem.

I printed items when next method is called, and is called in the first and second click (second not necessary in the button, no matter where in the screen)

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell

What could be happening?

Answer 1

Problem solved.

I had this problem when update to Swift4 and Xcode 9.0, but today I upgrade Xcode to 9.0.1 version (released yesterday) and collectionView.reloadData() is working again. So, if you have this problem ensure you have last Xcode version or wait until next version is released.

Answer 2

It is a temporary solution in swift4 (Xcode 9).

DispatchQueue.main.async {
  let numberOfItems = collectionView.numberOfItems(inSection: 0)
  let indexPaths = [Int](0..<numberOfItems).map{ IndexPath(row: $0, section: 0) }
  collectionView.reloadItems(at: indexPaths)
}