Video file is not ready when it's time to play it - ios

Question

New in ios, using Swift 2.0, I have video file in Amazon S3, I use HanekeSwift for download and "cache" that video file and then play it, the issue is that when I play the video, the file written by hakene it isn't yet available, so nothing plays (I'm reusing this player SCPlayer).
How can I get notified when that video file is ready and available for play it?
PS: I've tried using PromiseKit for "play it" in "future" but no luck :(, here the sample of code:
Main call:
// prepare the promise downloads and play first one
when(self.prepareDownloads()).then {
self.playVideo(0)
}
I used this function as a way to know wich videos has been downloaded, and before play the video check if exists inside self.downloaded dictionary
func prepareDownloads() {
if let videos = self.videos {
// iterate the video list for create all the promise
for (index, video) in videos.enumerate() {
let promise = { () -> Promise<NSURL> in
return Promise<NSURL> { fulfill, reject in
log.debug("download video \(index)")
// request the video and cache it
let cache = Shared.dataCache
let resource = NSURL(string: (reaction.objectForKey("resourceURL") as! String))!
cache.fetch(URL: resource).onSuccess { data in
// get the cached file
let location = NSURL(string: DiskCache.basePath())!.URLByAppendingPathComponent("shared-data/original")
let diskCache = DiskCache(path: location.absoluteString)
let file = NSURL(fileURLWithPath: diskCache.pathForKey(resource.absoluteString))
self.downloaded.updateValue(file, forKey: index)
fulfill(file)
}.onFailure { _ in
log.error("error downloading video")
}
}
}
// save it in dictionary
self.downloads.updateValue(promise, forKey: index)
}
}
}
Verify videos before play it
func playVideo(index: Int) {
// hasn't been downloaded?
if (self.downloaded[index] == nil) {
// call the promise to download and then play
if let promise = self.downloads[index] {
promise().then { path in
// play video
self.playMedia(index, filePath: path)
}
}
} else {
// the video has been downloaded
self.playMedia(index, filePath: (self.downloaded[index])!)
}
}
Play the video
func playMedia(index: Int, filePath path: NSURL) {
// play the specific video
self.player.setItemByStringPath(path.absoluteString)
// THIS PRINT "FALSE" CUZ FILE DONT EXISTS YET :/
print(NSFileManager.defaultManager().fileExistsAtPath(path.path!))
self.player.play()
log.debug("playing video \(index)")
}