Present preview of downloaded file directly in app

Question

My application have file download option which downloads the file using alamofire download method. When the download completes i need to present the preview of the file without saving it to internal/cloud storage. How can i achieve this whatsapp like function that shows the preview after downloading the file.

func downloadFile(fileUrl: URL) {
    let destination = DownloadRequest.suggestedDownloadDestination(for: .documentDirectory)

    Alamofire.download(fileUrl, to: destination)
        .response(completionHandler: { (downloadResponse) in
            self.dic.url = downloadResponse.destinationURL
            self.dic.uti = downloadResponse.destinationURL!.uti
            let rect = CGRect(x: 0, y: 0, width: 100, height: 100)
            self.dic.presentOpenInMenu(from: rect, in: self.view, animated: true)
        })
}

alamofire.download already downloads a file and save it to the destination you passs to it which is in your internal storage inside the app directory — Daniel Raouf, Jan 10 '19 at 12:18
Since i got the solution only after posting the thread, the reference of alamofire is there. You can directly assign your file location to `self.previewItem` as in reference. — Vaisakh KP, Jan 10 '19 at 12:46

Vaisakh KP · Accepted Answer · 2019-03-25T06:47:47.783

To present a preview of a file use Apple’s QuickLook framework that lets you embed previewing for a huge range of file types, including iWork documents, Microsoft Office documents, PDFs, images, and more, all without writing much code.

First, import the QuickLook framework, then make your view controller conform to the QLPreviewControllerDataSource protocol.

Reference:

Code:

class ViewController: UIViewController {
    var previewItem = URL!

    func downloadFile(fileUrl: URL) {
        let destination = DownloadRequest.suggestedDownloadDestination(for: .documentDirectory)

        Alamofire.download(fileUrl, to: destination)
        .response(completionHandler: { (downloadResponse) in

            let previewController = QLPreviewController()
            previewController.dataSource = self
            self.previewItem = downloadResponse.destinationURL
            self.present(previewController, animated: true, completion: nil)
        })
    }
}

extension ViewController: QLPreviewControllerDataSource {
    func numberOfPreviewItems(in controller: QLPreviewController) -> Int {
        return 1
    }

    func previewController(_ controller: QLPreviewController, previewItemAt index: Int) -> QLPreviewItem {
       return self.previewItem as QLPreviewItem
    }
}

score 1 · Answer 2 · answered Jul 03 '20 at 07:46

Here is one solution using Alamofire. Someone may help.

Steps:

Alamofire has excellent staff to direct download and also save/write your file into disc.
Return a path where downloaded file saved.
Using UIDocumentInteractionController pass the file path

Then present this view

 import Alamofire

     extension UIViewController : UIDocumentInteractionControllerDelegate{


     func downloadFileForPreview(fileName: String, fileExtension: String, filePath: String )  {


         let destination: DownloadRequest.DownloadFileDestination = { _, _ in
             let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]

             let fileWithExtension = "file.\(fileExtension)"

             let fileURL = documentsURL.appendingPathComponent(fileWithExtension)

             return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
         }
         //UtilitySwift.showUniversalLoadingView(true)
         Alamofire.download(filePath, to: destination).response {  response in
             debugPrint(response)
         //UtilitySwift.showUniversalLoadingView(false)

             if response.error == nil, let storeFilePath = response.destinationURL?.path {
                 //let image = UIImage(contentsOfFile: imagePath)
                 self.previewDocument(withFilePath: response.destinationURL)
                 print(storeFilePath)

             }

             else{
                 UtilitySwift.showErrorMessage(message: response.error?.localizedDescription ?? "Error occured when downloading" )
                 print(response.error?.localizedDescription ?? "")
             }

         }
     }


     //  Converted to Swift 5.1 by Swiftify v5.1.29672 - https://objectivec2swift.com/
     func previewDocument(withFilePath filePath: URL?) {

         var documentInteractionController: UIDocumentInteractionController?

         if filePath != nil {
             // Initialize Document Interaction Controller
             if let filePath = filePath {
                 documentInteractionController = UIDocumentInteractionController(url: filePath)
             }

             // Configure Document Interaction Controller
             documentInteractionController?.delegate = self as UIDocumentInteractionControllerDelegate

             //if not possible to open
             if !documentInteractionController!.presentPreview(animated: true) {
                 documentInteractionController?.presentOptionsMenu(from: CGRect.zero, in: self.view, animated: true)
             }

         } else {
             // error
             print("file preview error")
         }
     }
     //UIDocumentInteractionControllerDelegate
     public func documentInteractionControllerViewControllerForPreview(_ controller: UIDocumentInteractionController) -> UIViewController {
         self
     }

     }

Call from any UIViewController

self.downloadFileForPreview(fileName: "file", fileExtension: fileExt ?? "", filePath: REPLACE_WITH_DOWNLOAD_URL)

Present preview of downloaded file directly in app

2 Answers2

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