performBatchUpdates vs reloadData

performBatchUpdates and reloadData are both methods used in UITableView and UICollectionView to update their content, but they serve different purposes and have different behaviours.

1. performBatchUpdates(_:completion:):

• This method is used to perform a batch of updates to the table view or collection view.
• It allows you to insert, delete, or move sections and items in a single animation block.
• It provides a way to animate multiple changes together, providing a smoother user experience.
• Common use cases include inserting/deleting/moving multiple rows or sections at once.
• Example:

collectionView.performBatchUpdates({
    // Perform your batch updates here
    collectionView.insertItems(at: [IndexPath(item: 0, section: 0)])
}, completion: nil)

2. reloadData():

• This method reloads all of the data for the table view or collection view.
• It discards the current data and recreates all visible cells, headers, and footers.
• It’s typically used when the entire data set has changed or when the data structure has been modified in a way that requires a complete reload.
• Example:

tableView.reloadData()

Differences:

• performBatchUpdates is used for making batch updates to the table or collection view, such as inserting, deleting, or moving items, while reloadData reloads all data.
• performBatchUpdates provides smooth animations for batch updates, while reloadData reloads the entire table or collection view without animation.
• performBatchUpdates is more suitable for making specific changes to the content, while reloadData is more suitable for completely refreshing the content.

Space and Time Complexity:

• Both methods have similar time complexities in terms of performance, as they may involve updating the layout and rendering the visible cells. The time complexity depends on factors like the number of items, the complexity of the cell configuration, and the device’s hardware.
• The space complexity is also similar for both methods, depending on the amount of data being updated or reloaded. However, reloadData may consume slightly more memory since it recreates all visible cells, headers, and footers.