swift - SizeForItemAtIndexPath : get items standard size

Question

我在具有两个 Collection View 的 View Controller 中使用 sizeForItemAtIndexPath 函数。

如何在 sizeForItemAtIndexPath 函数中排除一个 Collection View ，或者如何在不更改任何内容的情况下获得原始单元格大小？

Answer 1

• 排除一个 Collection View

   func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        // to exclude one collection view
        if collectionView == collectionViewOne {}// first
       if collectionView.tag == number(you set before){}// second
  
       // to get the original cell size without changing anything
       //let yourSize = collectionViewLayout.itemSize
       //return collectionViewLayout.itemSize   // if you have set it globally, 
      /*
       But you can not get it, because itemSize is a property of UICollectionViewFlowLayout.
  
       And you can't cast collectionViewLayout to UICollectionViewFlowLayout Class which is kind of UICollectionViewLayout Class .
  
     Thats not how inheritance works.
    */    
  }
  

• 在不改变任何东西的情况下获得原始单元格大小

  let indexPath = IndexPath(item: number(you choose), section: number(you choose, 0 or 1))
  let layout = UICollectionViewFlowLayout() // you set
  // got the size
  // more generally, if you have set layout per item through delegate.
  let size = self.collectionView(collectionViewOne, layout: layout, sizeForItemAtIndexPath: indexPath)
  // or try this ,if you have configured globally
  let itemSize = layout.itemSize