UIButton text not updating

Question

A "tried and true" pattern I've used in my iOS Swift app is that I have several areas with UIButtons. When the button is pressed, it fires off some net code that connects to my API. While this is happening, I have the button text say "please wait, loading" and I disable the button. When the queued action finishes in my callback I have the button text enable and change back to the original state. It works great.

I recently added something not using NSURL/NSDATA (it's just a file writer). I copied all the same GCD queue code and oddly enough it doesn't update the button text.

Here is my code. When you tap the button, the text becomes invisible until the callback finishes, and then it just restores back. Oddly enough if I change my simulator to iPad Pro it actually works (??) and says "please wait, downloading". If I switch to iPhone 6s it doesn't work.

@IBAction func btnGenerateCSV(sender: UIButton) {

        //Grab the original text of the button to restore later after done
        let originalButtonText = sender.titleForState(UIControlState.Normal)

        //Localized is an extension function I wrote.
        //As you can see I got crazy here adding all the UI States as a last ditch attempt to see if that was the reason.
        sender.setTitle(Localized("Downloading"), forState: UIControlState.Normal)
        sender.setTitle(Localized("Downloading"), forState: UIControlState.Disabled)
        sender.setTitle(Localized("Downloading"), forState: UIControlState.Highlighted)
         //I've tried moving this before the setTitle. No avail.
            sender.enabled = false
//I've tried the other queues as well, and even just tried dispatch_async(dispatch_get_main_queue()) but no luck

dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INITIATED, 0)) { [unowned self] in

            CsvReportWriter.GenerateReport()
                {
                    r in
                    dispatch_async(dispatch_get_main_queue()) {
                        FileManager.WriteToFile(r, filename: self.filename)

                        if FileManager.FileExists(self.filename) {
                            self.docController = UIDocumentInteractionController(URL: FileManager.GetURLOfFile(self.filename))
                            self.docController.presentOptionsMenuFromRect(sender.frame, inView:self.view, animated:true)
                        }
                        //Restore button state and text b/c we're done
                        sender.enabled = true
                        sender.setTitle(originalButtonText, forState: UIControlState.Normal)
                    }

            }
        }  
    }

Any ideas? If I swap out the CsvReportWriter.GenerateReport() code with some other async code that does a call out to my API, it works.

Thanks so much!

Possibly a little off-topic, but note that in Swift 2, the `Self` for the `OptionSetType` members---for `forState` arguments such as the method `.setTitle` of `UIButton`---can be inferred, so you needn`t write `forState: UIControlState.Normal`; `forState: .Normal` suffices. Moreover, as you set the same title for three different states, `OptionSetType` allow you to set properties for all these states at once, e.g. `forState: [.Normal, .Disabled, .Highlighted]` in a single line. See http://stackoverflow.com/questions/34502753/arrays-of-enums-are-enums-in-swift/34503263#34503263 for details. — dfrib, Jan 02 '16 at 18:36

score 1 · Accepted Answer · answered Jan 02 '16 at 18:01

So I wanted to post an answer that I thought was interesting - I had a different account logged in to my iPad Pro simulator.. and noticed that the label correctly appeared. In iPhone 6 it did not. I was logged into a different account.

So what was the difference? There were about 1,000,000 test rows to generate in the iPad pro, and 3 in the iPhone, so everything finished so fast there was no UI to even update.

I introduced a delay just as a test, and noticed that in fact it works / exports so that's actually what it was.

So it turns out things were running so fast there wasn't even time to update to 'please wait' lol

Sorry to bother anyone but feel free to use the above code as it should be effective to do what you need :)

**Do not add delays to make code work.** Instead, find a way to notify the program that a task has been completed and it can move on. You may want to look into protocol methods, or even the `NSNotificationCenter`. — Zane Helton, Jan 02 '16 at 20:08
Hey just to be clear, I took the delay out (it was only a test). thanks though! — NullHypothesis, Jan 03 '16 at 05:30

UIButton text not updating

1 Answers1