My old app is having a problem with QLPreviewController on iOS11 that it suddenly can not preview any file while it worked just fine on iOS10, when I try to skip step to check if can preview the file I got below message:
Unsupported preview item type in -previewItemViewControllerClassWithStyle:; for preview item - [FileName] #PreviewItem.
I tried to create a test app to preview a same file and it worked, quite strange. I have spent a day on this and still not find out the root cause yet. Does anyone know the answer? Thanks.