call value variable from outside function in swift - swift

Question

I have a problems to call a variable in class, from outside function.
Swift gives me the following error: Use of unresolved identifier 'imageFilename'
How I can solve it? How should I get the value of the Filename variable?
My code:
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
if (collectionView == self.collectionView1)
{
let cell : FeaturedCollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier(self.reuseIdentifierFeatured, forIndexPath: indexPath) as! FeaturedCollectionViewCell
let imgURL: NSURL = NSURL(string: "http://localhost:9001/feature-0.jpg")!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request){
(data, response, error) -> Void in
if (error == nil && data != nil)
{
func display_image()
{
let imageFilename = UIImage(data: data!)
}
dispatch_async(dispatch_get_main_queue(), display_image)
}
}
task.resume()
cell.featuredImage.image = UIImage(named: imageFilename)
return cell
}
}
Image capture link

Answer 1

How about if you declare the variable outside of the function and inside of the function you set the value. Then you have access to the variable and its value.
Your Problem is definetly that you can not access the variable, because it is just know inside of the function.
Code:
try it like this...
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
if (collectionView == self.collectionView1)
{
let cell : FeaturedCollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier(self.reuseIdentifierFeatured, forIndexPath: indexPath) as! FeaturedCollectionViewCell
var imageFilename: UIImage
let imgURL: NSURL = NSURL(string: "http://localhost:9001/feature-0.jpg")!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request){
(data, response, error) -> Void in
if (error == nil && data != nil)
{
func display_image()
{
imageFilename = UIImage(data: data!)
}
dispatch_async(dispatch_get_main_queue(), display_image)
}
}
task.resume()
cell.featuredImage.image = UIImage(named: imageFilename)
return cell
}
}
Write me if this worked for you.

Answer 2

The scope of imageFileName is the function display_image in which it is declared, it is not visible outside that if. The problem is not the access of a variable in a class, your custom cell class doesn't seem to declare a variable named imageFileName
Edit
Why don't you set the image inside the completion closure?:
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
if (collectionView == self.collectionView1) {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(self.reuseIdentifierFeatured, forIndexPath: indexPath) as! FeaturedCollectionViewCell
let imgURL: NSURL = NSURL(string: "http://localhost:9001/feature-0.jpg")!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request) {
(data, response, error) -> Void in
if (error == nil && data != nil) {
dispatch_async(dispatch_get_main_queue()) {
cell.featuredImage.image = UIImage(data: data!)
}
}
}
task.resume()
return cell
}
}
Be aware that due to the fact that asynchronous request may complete in an undefined order and cell reuse, you can end up with incorrect images for cells, you could save the image url in the cell and check if it is the same as the one captured in the closure when the the closure completes.