SVProgressHUD not displaying until UITableView is displayed

Question

I am trying to use the SVProgressHUD to indicate that the app is busy.

My code is now:

        SVProgressHUD.show()
        DispatchQueue.global(qos: .background).async {
            parser.parse()
            print("start reloading")
            self.protocolTableView.reloadData()

            print("end reloading")
            SVProgressHUD.dismiss()
        }

I get this warning:

UITableView.reloadData() must be used from main thread only

And it takes quite a while before the tableView is displayed after the parsing has been done.

How can I update the tableView after reading in the parsing from the main thread?

Thanks, Bart

Not sure if this will work, but can you try putting the show() method in the prepareForSegue method? Or I think you could try running the show() call in the main thread.. — Skywalker, Nov 22 '17 at 02:46
I updated the code to move it to prepareForSegue(), but it seems that it is only executed on the main thread until the viewDidLoad() has finished. — Bart Schraa, Nov 22 '17 at 03:15
`SVProgressHUD.show()` already adds itself to main queue, no need to do it explicitly once again. — Nik Yekimov, Nov 22 '17 at 03:28

score 1 · Accepted Answer · answered Nov 22 '17 at 03:16

1

XMLParser.parse can block the UI. Try doing that on a background thread:

DispatchQueue.global(qos: .background).async {
    parser.parse()
}

answered Nov 22 '17 at 03:16

Tyler Bell

26
3

score 1 · Answer 2 · edited Nov 22 '17 at 05:44

1

UI updates should be done in main thread:

SVProgressHUD.show()
DispatchQueue.global(qos: .background).async {
    parser.parse()
    print("start reloading")

    DispatchQueue.main.async(execute: {() -> Void in
        self.protocolTableView.reloadData()
        SVProgressHUD.dismiss()
    })
}

edited Nov 22 '17 at 05:44

clemens

16,716
11
50
65

answered Nov 22 '17 at 05:35

Khairul Islam

61
3

score 0 · Answer 3 · answered Nov 22 '17 at 04:25

0

 DispatchQueue.main.async {
        self.protocolTableView.reloadData()
        }

Reload tableView in Main Thread.

answered Nov 22 '17 at 04:25

Syed Sadrul Ullah Sahad

1,182
9
15

For me it worked only properly when using DispatchQueue.main.sync instead of DispatchQueue.main.async – Bart Schraa Nov 22 '17 at 05:36

Bart Schraa · Answer 4 · 2017-11-22T05:35:51.970

0

This was the solution:

SVProgressHUD.show()
DispatchQueue.global(qos: .background).async {
    parser.parse()

    DispatchQueue.main.sync {
        self.protocolTableView.reloadData()
    }

    SVProgressHUD.dismiss()
}

Thanks for all the help!!

edited Nov 22 '17 at 05:35

answered Nov 22 '17 at 05:12

Bart Schraa

13
6

SVProgressHUD not displaying until UITableView is displayed

4 Answers4