How to show the progress of copying a large file in iOS?

Question

I am writing an iOS app. In my app, I want to copy some files from one folder to another. But because some files is too large, it will take a long time to finish the copy. So I want to add a progress bar to show the percentage of the copy. But I find that the file manager has no callback method to get the percentage. Does anyone have the good solution to it?

Answer 1

In high level :

1. Run your copying process in a seperate thread (T1)
2. Run another thread (T2) which reads periodically (say every 100ms) the destination file current_size.
3. Calculate the percentage : current_size / total_size
4. Update you progress bar ui element