Swift dispatch_async not updating UIView until iOS notification - ios

Question

I have a UIView that is updated from a server once a button is pushed.
The UIView update happens within a dispatch_async(). Through debugging I can see that the server response has been received and the new subview is created and applied to the UIView.
However the view remains unchanged UNTIL another iOS notification occurs (e.g. the device receives an email). As soon as the notification banner is displayed the UIView is refreshed and displays the image from the server.
What am I missing? How do I get the UIView to update as soon as the new subview is added?
Note: I have tried the following within and outside the dispatch_async() and tried calling them on the same queue after the initial change takes place without luck.
self.view.setNeedsDisplay()
self.view.bringSubviewToFront(view)
self.view.layoutIfNeeded() (thanks for the suggestion #buxik)
EDIT added code (small version of larger class, only relevant section added):
class networkedImage: UIViewController {
#IBOutlet var viewArea: UIView = UIView()
let originalWidth: CGFloat = 200
let originalHeight: CGFloat = 100
let imageURL: NSURL = NSURL(string: "www.example.com/image.jpg")!
func updateViewArea() {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) {
dispatch_async(dispatch_get_main_queue()) {
self.viewArea.subviews.forEach({ $0.removeFromSuperview() })
let newImageView = UIImageView(frame: CGRectMake(0, 0, self.originalWidth, self.originalHeight))
let data = NSData(contentsOfURL: self.imageURL)
if data != nil {
let image = UIImage(data: data!)
if image != nil {
newImageView.image = image
self.viewArea.addSubview(newImageView)
self.viewArea.bringSubviewToFront(newImageView)
self.viewArea.setNeedsDisplay()
}
NSNotificationCenter.defaultCenter().addObserverForName("NotificationIdentifier", object: nil, queue: nil, usingBlock: {
[unowned self] note in
print("I thought this might work, it didn't.")
})
}
}
}
}
}

Answer 1

To resolve the issue I added an Observer to viewDidLoad()
NSNotificationCenter.defaultCenter().addObserverForName("imageReadyNotification", object: nil, queue: NSOperationQueue.mainQueue(), usingBlock: {
[unowned self] note in
self.updateViewArea()
})
Then at the bottom of updateViewArea() I post the notification
if self.newImage == true {
NSNotificationCenter.defaultCenter().postNotificationName("imageReadyNotification", object: nil, userInfo: nil)
}
The if condition is to ensure the notification isn't fired continually. I have no idea why calling this function twice works, but it does.