Okay, I am trying to work out a pageview slider that retrieves images url from an API using this tutorial as a base.
I have already coded the asynchronous downloading of images and appending it to the pageImages array. That part works fine.
However, I received an error when I am trying to run the app in the simulator :
fatal error: unexpectedly found nil while unwrapping an Optional value
For some reason, fetching the JSON objects and populating the pageImages Array happens after I call my helper method viewControllerAtIndex.
my code
class ViewController: UIViewController, UIPageViewControllerDataSource {
var pageViewController: UIPageViewController!
var pageImages = NSArray()
var jsonData = NSArray()
override func viewDidLoad() {
super.viewDidLoad()
###THIS EXECUTES AFTER MY HELPER METHOD viewControllerAtIndex
self.fetchPublishers()
self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
self.pageViewController.dataSource = self
var startVC = self.viewControllerAtIndex(0) as ContentViewController
var viewControllers = NSArray(object: startVC)
self.pageViewController.setViewControllers(viewControllers as [AnyObject], direction: .Forward, animated: true, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 30, self.view.frame.width, self.view.frame.size.height)
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == 0 || index == NSNotFound) {
return nil
}
index--
return self.viewControllerAtIndex(index)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == NSNotFound) {
return nil
}
index++
if (index == self.pageImages.count) {
return nil
}
return self.viewControllerAtIndex(index)
}
func viewControllerAtIndex(index: Int) -> ContentViewController
{
if ((self.pageImages.count == 0) || (index >= self.pageImages.count)) {
return ContentViewController()
}
var vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController
vc.imageFile = self.pageImages[index] as! String
vc.pageIndex = index
return vc
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int
{
return self.pageImages.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int
{
return 0
}
func fetchPublishers () {
var req:Request = Alamofire.request(OauthToken.Router.ReadPublishers(""))
var aClosure = {(req:NSURLRequest, response:NSHTTPURLResponse?, JSON:AnyObject?, error:NSError?) -> Void in
if (error != nil) {
println(error)
println("Couldn't connection to server.")
} else {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) {
self.jsonData = JSON as! NSArray!
var baseUrl: String = "http://0.0.0.0:3000"
self.pageImages = JSON!.valueForKey("photo_url") as! NSArray!
###Prints/executes after
println(self.pageImages)
}
}
}
req.responseJSON(aClosure)
}
}
ContentViewController
class ContentViewController: UIViewController {
@IBOutlet weak var imageView: UIImageView!
var pageIndex: Int!
var imageFile: String!
override func viewDidLoad() {
super.viewDidLoad()
####THE ERROR HAPPENS HERE
self.imageView.image = UIImage(named: self.imageFile)
}
}
How can I fix this?
