Swift - 如何手动在屏幕外预加载 UITableViewCells？

Question

The UITableViewCells inside my UITableView contain a view (mainView) that has margins to all sides - so the mainView has space to the sides of the screen as well as to the other cells above and below.

The mainView has a shadow. This shadow exceeds the cell borders, but by setting "clipToBounds" to false, a part of the shadow is also visible on the next cell in the tableView - that's how I want it to be.

Now my problem:

When I'm scrolling up in the tableView, this happens: A dequeued cell (outside/above the screen), let's name it cell1 , loads because it has to be displayed next. This cell1 doesn't know, that the cell above that, let's name it cell0 , casts a shadow on cell1 . So, of course, it's showing no shadow when it becomes visible. The result is the shadow getting cut off, like this:

Screenshot

Is there any way to preload the views of the cells that have an impact on the cell that should be displayed next? Like: cell[i] is displayed right now, I'm scrolling up so cell[i - 1] is getting loaded but cell[i - 2] is getting loaded before that, so cell[i - 1] displays a part of the shadow cell[i - 2] is casting.

I hope you understand what my problem is. Thank you in advance!

Answer 1

First what do we have:

• cell cast shadow top (lets say) 5px
• cell cast shadow bottom (lets say) 15px
• cell's bottom shadow clips
• cell's content in the middle of cell (10 top offset, 10 bottom offset)

What we have to do:

• cell's content move top (5 top offset, 15 bottom offset) so cell would contain all it;s shadows