NSData is nil After AsynchronousRequest In Swift - swift

Question

I am trying to add video data to the HTTP Request's body but sometimes video data is turning to nil but sometimes not. Is there anything to fix this situation? When I delete the app from my app and after doing simulation again, nothing happened.
#IBAction func post(sender: AnyObject) {
let videodata = NSData(contentsOfURL: videoURL!)
let headers = [
"authorization": "Token \(userToken!)",
"content-type": "/*/",
"content-disposition": "attachment;filename=deneme.mp4",
"cache-control": "no-cache"
]
let request = NSMutableURLRequest(URL: NSURL(string: "http://molocate.elasticbeanstalk.com/video/upload/")!,
cachePolicy: NSURLRequestCachePolicy.ReloadIgnoringCacheData,
timeoutInterval: 10.0)
request.HTTPMethod = "POST"
request.allHTTPHeaderFields = headers
request.HTTPBody = videodata
let session = NSURLSession.sharedSession()
let dataTask = session.dataTaskWithRequest(request, completionHandler: { (data, response, error) -> Void in
if (error != nil) {
print(error)
} else {
//print(NSString(data: data!, encoding: NSUTF8StringEncoding))
do {
let result = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers)
print("Result -> \(result)")
let statue = result["result"] as! String
if(statue == "success"){
let videoId = result["video_id"] as! String
let videoUrl = result["video_url"] as! String
print(videoUrl)
let json = [
"video_id": videoId,
"video_url": videoUrl,
"caption": "This city is awesome:)",
"category": "travel",
"tagged_users": [["username": "amertturker"]],
"location": [
[
"id": "mekmaekfmaıhjagej3ıo45j3kt348t3gkg",
"latitude": "35.342643",
"longitude": "32.345236",
"name": "Milas Merkez Kafasına göre herkes",
"address": "Milas aq"
]
]
]
let newheaders = [
"authorization": "Token \(userToken!)",
"content-type": "application/json",
"cache-control": "no-cache"
]
do {
let jsonData = try NSJSONSerialization.dataWithJSONObject(json, options: .PrettyPrinted)
print(NSString(data: jsonData, encoding: NSUTF8StringEncoding))
// create post request
let url = NSURL(string: "http://molocate.elasticbeanstalk.com/video/update/")!
let request = NSMutableURLRequest(URL: NSURL(string: "http://molocate.elasticbeanstalk.com/video/update/")!,
cachePolicy: .UseProtocolCachePolicy,
timeoutInterval: 10.0)
request.HTTPMethod = "POST"
request.allHTTPHeaderFields = newheaders
request.HTTPBody = jsonData
let task = NSURLSession.sharedSession().dataTaskWithRequest(request){ data, response, error in
print(response)
//print(NSString(data: data!, encoding: NSUTF8StringEncoding))
dispatch_async(dispatch_get_main_queue(), {
if error != nil{
print("Error -> \(error)")
return
}
do {
let result = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments)
print("Result -> \(result)")
} catch {
print("Error -> \(error)")
}
})
}
task.resume()
} catch {
print(error)
}
} else{
// self.displayAlert("Hata", message: result["result"] as! String)
// UIApplication.sharedApplication().endIgnoringInteractionEvents()
// self.activityIndicator.stopAnimating()
// self.activityIndicator.hidesWhenStopped = true
}
} catch {
print("Error -> \(error)")
}
}
})
dataTask.resume()
do {
try NSFileManager.defaultManager().removeItemAtPath(videoPath!) //.removeItemAtURL(fakeoutputFileURL!)
dispatch_async(dispatch_get_main_queue()) {
print("siiiiil")
self.performSegueWithIdentifier("finishUpdate", sender: self)
}
} catch _ {
}

Answer 1

Your calling the httprequest asynchronously and then trying to use the data on the calling thread. It hasn't been populated until after the http request has returned which will occur at an undetermined future time. Anything you want to do with videoData should be done inside the completion handler, otherwise you are in a race condition and it might be nil when you call it.