UIDocumentInteractionController does not work

Question

In my application I download files of various formats. I'm trying to get the UIDocumentInteractionController to get the applications that can open this format. The problem is that the UIDocumentInteractionController is not working. This is my code:

func loadArchiveAtIndex(sender: NSNotification){
        let itemIndex = sender.userInfo!["index"] as! Int
        let archiveKey = sender.userInfo!["downloadKey"] as! String

        self.downloadingItens.append(itemIndex)
        print(archiveKey)

        let qualityOfServiceClass = QOS_CLASS_BACKGROUND
        let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
        dispatch_async(backgroundQueue, {

            SQLiteDataController().getTokenSincronismo({
                (Valido, Retorno, Token, Tipo) -> Void in
                if Valido == true{
                    switch Retorno {
                    case 9: // Retorno Válido
                        print(Token)

                        let params = [
                            "tokenSincronizacao":"\(Token)",
                            "chaveProdutoBiblioteca":"\(archiveKey)"
                        ]
                        Alamofire.request(.GET, "\(_URLPREFIX)/ObtemProdutoBiblioteca", parameters: params).responseJSON { (response) in
                            if response.result.isFailure {
                                print(response.result.error)
                            } else {
                                let result = response.result.value
                                if let archive = result?["ProdutoBiblioteca"] as? NSDictionary{
                                    let bytes = archive.objectForKey("Arquivo") as! String
                                    let name = archive.objectForKey("NomeArquivo") as! String
                                    let data = NSData.init(base64EncodedString: bytes, options: .IgnoreUnknownCharacters)
                                    let url = NSURL.init(string: name.lowercaseString)
                                    data?.writeToURL(url!, atomically: true)

                                    let documents = try! NSFileManager.defaultManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: false)
                                    let fileURL = documents.URLByAppendingPathComponent((name.lowercaseString))
                                    print(fileURL)

                                    let dic = UIDocumentInteractionController.init(URL: fileURL!)
                                    dic.delegate = self
                                    dic.presentPreviewAnimated(true)
//
                                    dispatch_async(dispatch_get_main_queue(), { () -> Void in
                                        var arrayIndex = 0
                                        for item in self.downloadingItens {
                                            let i = item
                                            if i == itemIndex {
                                                self.downloadingItens.removeAtIndex(arrayIndex)
                                                NSNotificationCenter.defaultCenter().postNotificationName("reloadTable", object: nil, userInfo: ["itens":self.downloadingItens])
                                                break
                                            }
                                            arrayIndex = arrayIndex + 1
                                        }
                                    })

                                }
                            }
                        }

                        break
                    default:
                        self.showError("Atenção", message: "Não foi Possivel Processar a sua Solicitação")
                        break
                    }
                }else{
                    self.showError("Atenção", message: "Não foi Possivel Processar a sua Solicitação")
                }
                }, sincFull:true)
        })
    }

    func documentInteractionControllerViewForPreview(controller: UIDocumentInteractionController) -> UIView? {
            return self.view
        }

What am I doing wrong?

Answer 1

You need to present the view from the main thread.

Instead of:

let dic = UIDocumentInteractionController.init(URL: fileURL!)
dic.delegate = self
dic.presentPreviewAnimated(true)

Try:

dispatch_async(dispatch_get_main_queue(), { () -> Void in
   let dic = UIDocumentInteractionController.init(URL: fileURL!)
   dic.delegate = self
   dic.presentPreviewAnimated(true)                                    
})