如何快速实现类似于Dropbox的进度视图？

Question

the Dropbox iOS app has a really cool sort of view hierarchy where, when a row is selected from their "Files" tableView, it segues into a view that shows the loading progress of the selected file, then that view transitions into the PDF reader where the file is read/viewed.

The video in this link shows exactly what I mean. Its like the progress view transitions into the PDF view rather then segue to it, because as you can see from the video, when you press the back navigation item from the PDF reader, it goes right back to the tableView, not the progress screen. How do they get this effect? How would I implement it myself?

Answer 1

Three controllers (master view -> progress view -> pdf reader) is possible ... you'd need to intercept the tap on the back button, and instead of going one step back (to the progress view) you'd want to step back two controllers.

But you'd be fighting iOS the whole way and giving yourself a headache.

Dropbox probably have two controllers master view -> detail view and follow some logic like this:

• viewWillAppear of the detail view they probably set up the progress view that occupies the full width and height of the screen.

• viewDidLoad of the detail view start the animation of the progress view.

• start download of the PDF file and update the progress indicator as it's downloaded.

• when fully downloaded add it to the view (but below the progress indicator)

• then hide the progress view to show the PDF view underneath.

Hope that gives you some ideas about how to create that effect.