Present preview of downloaded file directly in app - ios

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)
})
}

Answer 1

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:
https://www.hackingwithswift.com/example-code/libraries/how-to-preview-files-using-quick-look-and-qlpreviewcontroller
https://github.com/gargsStack/QLPreviewDemo
https://www.appcoda.com/quick-look-framework/
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
}
}

Answer 2

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)