Swift UIPageViewController & UIActivityIndicatorView - ios

Question

Is anyone aware of an issue with stopping a UIActivityIndicatorView (AI) / removing a UIView that has been added to a UIPageViewController?
I am showing the AI using:
override func viewWillLayoutSubviews() {
actInd.frame = CGRectMake(0,0, 80, 80)
actInd.center.x = self.view.center.x
actInd.center.y = self.view.center.y - 40
actInd.hidesWhenStopped = true
actInd.layer.cornerRadius = 5
actInd.alpha = 0.5
actInd.backgroundColor = UIColor.blackColor()
actInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.WhiteLarge
self.view.addSubview(actInd)
actInd.startAnimating()
// This next line prints out the details of each subview on the page for testing purposes
listSubviews(self.view)
I am also, for testing purposes, adding a blank UIView to the view using:
aView.frame = CGRectMake(0, 0, 200, 200)
aView.backgroundColor = UIColor.blueColor()
self.view.addSubview(aView)
}
Then I send my Parse.com query using a delegate to advise the UIPageViewController (e.g. this view) when the data is ready. This is working fine and I have tested that the data returns correctly, and that the expected method is being called.
In this method I try to stop the UIActivityViewController & try to hide aView:
self.actInd.stopAnimating()
aView.removeFromSuperView()
This didn't work so I tried:
self.actInd.removeFromSuperView()
This didn't work either. So I then tried to search through the subviews on the current view using:
func populateBoards(boards: [Board]) {
println(self.actInd) // PRINT LINE 1
var subviews = self.view.subviews
for v in subviews {
if v.isKindOfClass(UIActivityIndicatorView) {
println("YES, it is an activity view indicator \(v)") // PRINT LINE 2
v.stopAnimating()
v.removeFromSuperview()
}
}
self.boards = boards
println("Populated Boards!") // PRINT LINE 3
}
PRINT LINE 1 outputs: >
PRINT LINE 2 outputs: YES, it is an activity view indicator >
PRINT LINE 3 outputs: "Populated boards!"
EDIT:
The UIPageViewController is setup with the following code (in case it helps):
func setupUIPageView() {
self.pageViewController = UIPageViewController(transitionStyle: UIPageViewControllerTransitionStyle.Scroll, navigationOrientation: UIPageViewControllerNavigationOrientation.Horizontal, options: nil)
self.pageViewController.delegate = self
self.pageViewController.dataSource = self
var startVC = self.viewControllerAtIndex(0) as ViewController
var viewControllers:[ViewController] = [startVC]
self.pageViewController.setViewControllers(viewControllers, direction: .Forward, animated: true, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height)
self.pageViewController.view.alpha = 0.0
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
Help! Thanks all in advance :D

Answer 1

You should call all your UI related code on the main queue. Your Parse query is async and the completion block might be called on a different thread.
Wrap this call in this block:
NSOperationQueue.mainQueue().addOperationWithBlock {
self.actInd.stopAnimating()
}