Custom UICollectionView Layout-entry, uicollectionview Layout

Custom UICollectionView Layout-entry, uicollectionview Layout
Custom UICollectionView Layout-entry 0. application scenarios:

Various cells are often used in projects. Sometimes custom cells cannot meet product requirements. We can choose a complicated and difficult development method to solve the problem, of course, you can also choose a simple but skillful solution. The custom UICollectionView layout is a good way. This section describes how to use the custom UICollectionView layout to create a beautiful interface.

1. Inheritance plan

• 1> inherit from UICollectionViewLayout
• 2> inherit from UICollectionViewFlowLayout

2. methods that may need to be rewritten

• 1> prepareLayout

  • Set some initialization parameters here to perform initialization.
  • You must call [super prepareLayout];

• 2> layoutAttributesForElementsInRect:

  • The returned array contains the UICollectionViewLayoutAttributes object.
  • Return the layout attribute of all elements (such as cell) in collectionView: This method determines how the cell is arranged.
  • Each cell has its own layout attribute: UICollectionViewLayoutAttributes

• 3> shouldInvalidateLayoutForBoundsChange:

  • Whether to refresh the layout when the bounds of the uicollectionView changes
  • Once you refresh the layout, the methods 1> and 2> are called in sequence.

• 4> targetContentOffsetForProposedContentOffset: withScrollingVelocity:

  • The returned value of this method determines the final offset of collectionView (the final position)
  • ProposedContentOffset parameter: the offset of collectionView.
  • Velocity parameter: Rolling rate of collectionView

• 5> layoutAttributesForItemAtIndexPath:

  • If you inherit UICollectionViewLayout, you 'd better implement this method.
  • Purpose: return the layout attribute of the cell in the indexPath position.

PS: code will be uploaded later.