I have submitted the following as a bug, but I thought it would useful for the dev community to have a test app to demonstrate the issue.
QLPreviewController behavior changed in recent releases of ios 11. It will fail to preview a file depending on if the files are located in the main bundle or possibly the caches folder . Further the QLPreviewController will no longer reliably display files when used as a subview.
Steps to Reproduce:
1) build test app found at https://github.com/vinthewrench/QLPreviewTest
2) run on device - select a variety of sample numbers files.
3) Try again using "Use NSCachesDirectory" and "Use SubView" options
Expected Results: 1) file should display with Use SubView option.
Actual Results: 1) when running with NSCachesDirectory option off, we get the following log message. [default] Couldn't issue file extension for url: file:/
if you preview from the NSCachesDirectory (must copy the file there) a file will preview..
2) try the NSCachesDirectory on and Use Subview ON. The app preview will fail and you will get multiple log entries of [default] View service did terminate with error: Error Domain=_UIViewServiceInterfaceErrorDomain Code=3 "(null)" UserInfo={Message=Service Connection Interrupted} #Remote
Version/Build: Version 9.2 (9C40b) iOS 11.2.2 (15C202) Configuration: Model: iPhone 8 (Model A1863, A1905, A1906, A1907)
