How to add image to QuickLook that is stored in variable - ios

Question

I would like to add a couple of images that are stored in variables to a QLPreviewController. The QuickLook datasource requires a fileURL which I'm not sure how to get for an image that is stored in a variable and not in disk or in the project.
Any pointers as to how I can solve this issue?

Answer 1

Below code can be used to to display image file from local and from URL in QLPreviewController.
import UIKit
import QuickLook
class ViewController: UIViewController {
lazy var previewItem = NSURL()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func displayLocalFile(_ sender: UIButton){
let previewController = QLPreviewController()
// Set the preview item to display
self.previewItem = self.getPreviewItem(withName: "bull.png")
previewController.dataSource = self
self.present(previewController, animated: true, completion: nil)
}
#IBAction func displayFileFromUrl(_ sender: UIButton){
// Download file
self.downloadfile(completion: {(success, fileLocationURL) in
if success {
// Set the preview item to display======
self.previewItem = fileLocationURL! as NSURL
// Display file
DispatchQueue.main.async {
let previewController = QLPreviewController()
previewController.dataSource = self
self.present(previewController, animated: true, completion: nil)
}
}else{
debugPrint("File can't be downloaded")
}
})
}
func getPreviewItem(withName name: String) -> NSURL{
// Code to diplay file from the app bundle
let file = name.components(separatedBy: ".")
let path = Bundle.main.path(forResource: file.first!, ofType: file.last!)
let url = NSURL(fileURLWithPath: path!)
return url
}
func downloadfile(completion: #escaping (_ success: Bool,_ fileLocation: URL?) -> Void){
let itemUrl = URL(string: "https://developer.apple.com/wwdc20/images/hero/memoji/large/L7_2x.jpg")
// then lets create your document folder url
let documentsDirectoryURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
// lets create your destination file url
let destinationUrl = documentsDirectoryURL.appendingPathComponent("filename.jpg")
// to check if it exists before downloading it
if FileManager.default.fileExists(atPath: destinationUrl.path) {
debugPrint("The file already exists at path")
completion(true, destinationUrl)
// if the file doesn't exist
} else {
// you can use NSURLSession.sharedSession to download the data asynchronously
URLSession.shared.downloadTask(with: itemUrl!, completionHandler: { (location, response, error) -> Void in
guard let tempLocation = location, error == nil else { return }
do {
// after downloading your file you need to move it to your destination url
try FileManager.default.moveItem(at: tempLocation, to: destinationUrl)
print("File moved to documents folder")
completion(true, destinationUrl)
} catch let error as NSError {
print(error.localizedDescription)
completion(false, nil)
}
}).resume()
}
}
}
//MARK:- QLPreviewController Datasource
extension ViewController: QLPreviewControllerDataSource {
func numberOfPreviewItems(in controller: QLPreviewController) -> Int {
return 1
}
func previewController(_ controller: QLPreviewController, previewItemAt index: Int) -> QLPreviewItem {
return self.previewItem as QLPreviewItem
}
}