Download Multiple File at a time in Swift - swift

Question

I was finally able to download 1 video from a server using the following code:
import UIKit
class ViewController: UIViewController, NSURLConnectionDelegate {
var file:NSFileHandle?
#IBOutlet weak var webView: UIWebView!
override func viewDidLoad() {
super.viewDidLoad()
downloadVideo()
}
func downloadVideo(sender: UIButton) {
let urlPath: String = "http://www.ebookfrenzy.com/ios_book/movie/movie.mov"
var url: NSURL = NSURL(string: urlPath)!
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: true)!
connection.start()
}
func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
var fileName = "test.mov"
var fileAtPath = fileInDocumentsDirectory(fileName)
if(NSFileManager.defaultManager().fileExistsAtPath(fileAtPath) == false)
{
NSFileManager.defaultManager().createFileAtPath(fileAtPath, contents: nil, attributes: nil)
}
file = NSFileHandle(forWritingAtPath: fileAtPath)!
if ((file) != nil){
file!.seekToEndOfFile()
}
}
func connection(connection: NSURLConnection!, didReceiveData data: NSData!){
//write,each,data,received
if(data != nil){
if((file) != nil){
file!.seekToEndOfFile()
}
file!.writeData(data)
}
}
func connectionDidFinishLoading(connection: NSURLConnection!) {
file!.closeFile()
}
func documentsDirectory() -> String {
let documentsFolderPath = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)[0] as String
return documentsFolderPath
}
func fileInDocumentsDirectory(filename: String) -> String{
return documentsDirectory().stringByAppendingPathComponent(filename)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
But I need to download a lot of video files(I have at least 100 URL), how can I do it? I was thinking of doing it one at a time but I guess that in that approach I will have a lot of NSURLConnections instances and maybe I will eat all my RAM, Can you please help me to learn the right form of multiple files download?
Thank you so much!

Answer 1

You can use a concurrent queue to limit the max number of connections at a time.
func downloadVideo(sender: UIButton) {
for urlPath in urlPaths {
dispatch_async(dispatch_get_global_queue(QOS_CLASS_UTILITY, 0)) {
var url: NSURL = NSURL(string: urlPath)!
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: true)!
connection.start()
}
}
}
If you want to customize the max number of connections, check here:
Can I limit concurrent requests using GCD?