Parse in swift is very slow - my programming at fault ? - ios

Question

I have a main class in Parse, which feeds a table view in swift. the background image covers the whole of the background. These images are 480k in size. They do not always turn up on the tableviewcell (I know I can add an placeholder image). I have a very faster connection to my mobile.. If i use 4g they don't even turn up at all.
Here is my function for pulling the images down. I don't really know what else I can do.
func loadImages() {
var query = PFQuery(className: "TableViewData")
query.orderByDescending("objectId")
query.findObjectsInBackgroundWithBlock ({(objects:[AnyObject]!, error: NSError!) in
if(error == nil){
let imageObjects = objects as [PFObject]
for object in objects {
let thumbNail = object["backgroundImage"] as PFFile
thumbNail.getDataInBackgroundWithBlock({
(imageData: NSData!, error: NSError!) -> Void in
if (error == nil) {
let image = UIImage(data:imageData)
self.CellBackgroundImage.append(image!)
println(self.CellBackgroundImage.count)
}
})
}
}
else{
println("Error in retrieving \(error)")
}
})
}
As you can see I add them as a an array and the tableview will show them according to the index.path.
Can anyone suggest anything ?

Answer 1

Updates to the user interface must always be performed on the main thread. Asynchronous networking completions are typically called on a background thread (not sure about PFQuery stuff), so you need to force the update to happen on the correct thread:
dispatch_async(dispatch_get_main_queue()) {
self.CellBackgroundImage.append(image!)
}