CODEWITHSUNDEEP
iosobjective-cuitableviewswift
Halfpint
Halfpint

Reputation: 4079

iOS: Tableview Begin updates never plays animation

I have written some code to delete a post from the back end and local data storage when a user long presses a cell and confirms the change. However the tableview does not update. I have breakpointed my code and the tableView manipulation code is executed, why is my row not being removed from the view?

let alertView = UIAlertController(title: "Really?", message: "Are you sure you want to delete this post? Once you do it will be gone forever.", preferredStyle: .Alert)
    alertView.addAction(UIAlertAction(title: "Delete Post", style: UIAlertActionStyle.Default, handler: { (alertView:UIAlertAction!) -> Void in
        let p = post.getRawPost()
        p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
            // Remove from the local datastore too
            p.fetchFromLocalDatastore()
            p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
                // Update the table view
                self.tableView.beginUpdates()
                self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
                self.tableView.endUpdates()
        })

    })
}))

As I understand it, beginUpdates and endUpdates is used to update specific sections of a tableView without needing to perform a full reloadData call on the source. Am I missing something here?

UPDATE I moved the tableView update code to the main thread, this produced a crash whenever endUpdates is called. My new code looks as below, and is called on the main thread:

self.tableView.beginUpdates()
self.tableView.deleteRowsAtIndexPaths([NSIndexPath(forRow: indexPath.row, inSection: indexPath.section)], withRowAnimation: UITableViewRowAnimation.Automatic)
self.tableView.endUpdates()

Upvotes: 1

Views: 834

Answers (1)

Kjuly
Kjuly

Reputation: 35131

Wrap the code snippet below in MAIN THREAD instead:

self.tableView.beginUpdates()
self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
self.tableView.endUpdates()

EDIT for the crash

p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
   // Remove from the local datastore too
   p.fetchFromLocalDatastore()

   // Delete the desired item from array
   ...
   // Remove cell that the item belong to animated in main thread
   dispatch_async(dispatch_get_main_queue(), {
       // Update the table view
       self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
   })
})

Upvotes: 1

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