Document-Based Application - ios

Question

Xcode 9 / iOS 11:
My app creates pdf-files which are rendered with data from a core data-database. The pdf's are created from a WebView and are stored in the documents directory. Everything works so far. I can open the pdf-files in Apple's Files App and even edit them there. I would like to implement the DocumentBrowserViewController in my app. I used the template from Xcode 9. I'm not able to show the created pdf-files in the DocumentViewController like in Apple's Files App. I can pick the documents but the DocumentViewController shows only the file name and a done-button. Which is the easiest way to show existing pdf's in this DocumentViewController from the template? Where do I have to implement the relevant code?
Code from Xcode9-template:
class DocumentViewController: UIViewController {
#IBOutlet weak var documentNameLabel: UILabel!
var document: UIDocument?
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
// Access the document
document?.open(completionHandler: { (success) in
if success {
// Display the content of the document, e.g.:
self.documentNameLabel.text = self.document?.fileURL.lastPathComponent
// --> How to show/load the pdf here? Do I have to create a UIView here first?
} else {
// Make sure to handle the failed import appropriately, e.g., by presenting an error message to the user.
}
})
}
and here's the subclass of UIDocument from the Xcode 9-template:
class Document: UIDocument {
var pdfData: PreviewViewController?
override func contents(forType typeName: String) throws -> Any {
// Encode your document with an instance of NSData or NSFileWrapper
return Data()
}
override func load(fromContents contents: Any, ofType typeName: String?) throws {
// --> do I have to load the pdf here?
}
}
I'm not very experienced in app-development. I was watching Paul Hagerty's course cs193p on iTunesU about persistence with UIDocument. But he's saving the model of the app and I have a pdf. Is there an easy way to do show the pdf's? I tried different ways to load the pdf but I'm not sure if I have to create a UIView first. The nice feature in Files App is that you can edit or send the pdf via email.

Answer 1

A great resource for UIDocumentBrowserViewController is the WWDC video from 2017:
Building Great Document-based Apps in iOS 11 - WWDC 2017
To answer your question in your comment in func load. Yes you get your pdf here as Data:
override func load(fromContents contents: Any, ofType typeName: String?) throws {
guard let data = contents as? Data else { return }
}
But what you should do is in your DocumentViewController is to load the fileURL which is a property of UIDocument into a UIWebView which can easily display pdf files. Have a look here: https://stackoverflow.com/a/38792456/4089350
Then in your document.open function pass the fileURL to your UIWebView.