CODEWITHSUNDEEP
iosuitableview
Tomasu
Tomasu

Reputation: 181

Variable sized UITableViewCells

I have somewhat of an odd problem. I've already got a UITableView setup with custom heights for my table cells. The problem comes in when the content is loaded in the background for the cells. I need the cells to load asap, but theres a big image for each cell, that may take some time to load (from the network or flash), so the load is started in the background when the cell is first loaded. This means that the height for the cell is initially wrong, and needs to be updated later with a minimum of glitching. The problem I'm having is that it doesn't always want to update the table, or the image, and can cause some excess scrolling.

It's also incredibly slow. I have some optimizations I need to do to make it a bit less slow (make smaller copies of the main image, and cache the height for the cells temporarily).

I've tried all sorts of things. I make sure the table is told to update in the main thread, I've tried a bare set of beginUpdates/endUpdates, reloadRows/reloadSections (table is in grouped mode, with one row per section). I have yet to get the table to update properly once the image has finished loading.

If anyone has some insight into how to get this to work as smoothly as possible I'd appreciate it.

Upvotes: 0

Views: 107

Answers (1)

Ismael
Ismael

Reputation: 3937

The place to go is your heightForRowAtIndex: method. It needs to know if the image exists or not and return a value accordingly. Every time each row finishes loading it's image, you should call reloadRows~ method like this:

NSArray *indexPaths = [NSArray arrayWithObject:[NSIndexPath indexPathForRow:x inSection:y]];
[self.tableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationFade];

I'm not entirely sure if this will cause some heavy scrolling on your tableView, but it's an option.

Another option is to update in chunks. Say every 5-10 images (depending on how many you have) that get loaded reload their respective rows with that same method.

Upvotes: 1

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