UIActivityView Swift not functioning correcting? - ios

Question

#IBAction func getData(sender: AnyObject) {
activitySpinner.startAnimating();
activitySpinner.hidden = false;
edisonArray[0].EdisonLocation = edison1Location.text!;
edisonArray[1].EdisonLocation = edison2Location.text!;
edisonArray[2].EdisonLocation = edison3Location.text!;
edisonArray[3].EdisonLocation = edison4Location.text!;
edisonArray[4].EdisonLocation = edison5Location.text!;
edisonArray[0].EdisonComment = edison1Comment.text!;
edisonArray[1].EdisonComment = edison2Comment.text!;
edisonArray[2].EdisonComment = edison3Comment.text!;
edisonArray[3].EdisonComment = edison4Comment.text!;
edisonArray[4].EdisonComment = edison5Comment.text!;
for(var i = 0; i < edisonArray.count ; i++){
var edison = edisonArray[i];
edison = startDataCollection(edison);
edisonArray[i] = edison;
}
edison1Data.text = "True"
edison2Data.text = "True"
edison3Data.text = "True"
edison4Data.text = "True"
edison5Data.text = "True"
if(!edisonArray[0].EdisonBool) { edison1Data.text = "False" }
if(!edisonArray[1].EdisonBool) { edison1Data.text = "False" }
if(!edisonArray[2].EdisonBool) { edison1Data.text = "False" }
if(!edisonArray[3].EdisonBool) { edison1Data.text = "False" }
if(!edisonArray[4].EdisonBool) { edison1Data.text = "False" }
activitySpinner.stopAnimating();
activitySpinner.hidden = true;
}
The code above is for a project I'm working on. I'm trying to get the activity spinner working every time I run this code the spinner is not animating. Can someone please help me with this.
activitySpinner is an object of UIActivityIndicatorView

Answer 1

You are running your work in the main thread. Which will stop the animation from working correctly. Additionally, you are calling start and stop animation on the same frame of the runloop. Which can also cause it to not animate.
Finally, you can not update the user interface of the background thread. So if you are working with UIKit controls you will need to do so on the main thread.
Matt points out the correct method of invoking again on the main thread. But I suspect the full workflow would look like this
activitySpinner.startAnimating();
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);())
{
//do any slow operations here in the background queue
doProcess();
//move back to the ui thread
dispatch_async(dispatch_get_main_queue())
{
//update any user interface info based on the above processing
updateUi();
activitySpinner.stopAnimating();
}
}

Answer 2

Like this:
#IBAction func getData(sender: AnyObject) {
activitySpinner.startAnimating();
dispatch_async(dispatch_get_main_queue()) { // <--
activitySpinner.hidden = false;
edisonArray[0].EdisonLocation = edison1Location.text!;
// ...
activitySpinner.stopAnimating();
activitySpinner.hidden = true;
}
}
But note that this will not make your code correct. If startDataCollection is time-consuming, you should not be doing it on the main thread. However, that's another question.