I don't believe there's a way to do this. I'm not very familiar with the framework you linked to, but I work full-time on the PSPDFKit iOS PDF SDK. To render PDF's on iOS, they need to be fully downloaded. You basically create a CGPDFDocument at some point either via
CGPDFDocumentCreateWithURL(...)
(or)
CGPDFDocumentCreateWithProvider(...)
Now CoreGraphics will throw out some cryptic error 15 if you try to feed CGPDFDocumentCreateWithURL with a remote URL (although it does work for /localhost/ remote URLs)
You theoretically could write a CGDataProvider that downloads the document on the fly, but the trouble is that iOS still will read and parse the whole PDF before it can display it - and I went through the trouble of writing a custom provider myself (one that supports AES256 and decrypts PDF content on the fly for extra security). It's really tricky to get it right.
tl,dr: You need to download the PDF. For example with this neat AFNetworking extension I wrote - it even supports resume.