In the Mac OS Mojave Preview app, it is easy to share PDF files into a separate document and also merge PDF files into one document. So, let's take a look at a copy of PDF that has four pages in it. If you do not see the left sidebar here, click here, and instead of having Hide Sidebar, select Thumbnails. Now you can see that there are four pages here and you can click on someone to see the page. So let's say we'll share this in two separate PDFs. One with the first two pages and one with the other two sides. There are many different ways to do this.
For example, we can only delete the pages from this. So I can grab the third page and keep the command key and take the fourth page. Press the Delete key and now I have a document with the first two pages. So it would work in some cases. Enter Command Z to undo it. I could also do the same first with the first two pages, the command clicks on each one, and click Delete and now the third and fourth pages are the two pages there. So I can basically duplicate the file and do it for everybody to get what I want.
A finer way would be to use Copy and Paste. So I'll do the command, select the first two pages and make command C for copy or just edit copy. Then file New from clipboard or command N. This creates a new document that has the first two pages in there. So I'll save it. Command S. I'll just save it on the desktop as Demo 1
You can also do this with Drag and Drop. So I can command and choose these two first pages here. Drag them and it creates a document where it has the two. I can command, select them and drag them and now I have two documents here. Pages 1 and 2. Pages 3 and 4. So very easy ways to create PDF files by dividing the pages into an existing PDF.
So let's say we want to merge two documents together. So let's merge those two that we've created. I will do that by opening the first one, and then there is an easy way to do that just drag and drop the other one into the left thumbnail here. Just drag it after it. You can see that I can actually insert it between existing pages. Now I have what I want, but I only save it as a new version of the first document. Which may not be what I want because I might want to keep the first document and the second document and make a whole new one. So let me Undo it, and I have the first document just as I had before.
Let me choose both of these pages here. I'll copy and then make a new one from the clipboard. Now there is a bug in Preview. When you do, you get two versions, two documents, untitled 1 and untitled 2 here on the left sidebar, and it only happens when you select all the pages in the PDF file and make Copy and New from the clipboard. So to fix this error, I'll close the other document here. This untitled 2. I'll click on the first page of it, go to File, and close the selected PDF document. Don't close the window, but this one. It will only get rid of the unnecessary other copy.
Now I have an untitled document with two pages. I can go and drop this in here, and now I have a document with all four pages. I can save and I save it as a Demo copy and it puts it there. So now I have a merged document with them. You can also copy and copy the first document. So I can choose it and make the file, this is in the Finder. File, duplicate. Now I have this copy here, and I can open it and drag the other into it.
I can also open the second document, if I want, select the pages where I want and drag them from one document to another. So this gives you more flexibility because now I can actually go and select a few pages from one, a few pages from the other, and create a new document. Save it. So, for example, I could open this document here, let me choose page 2. I'll do the Copy and New from the clipboard. There is page 2. I open the second document and I choose page 4. Actually, I want to go from here to the thumbnail line here and I have created a document that is page 2 and page 4 now from there. So you can use Drag and Drop from the thumbnails sidebar to basically mix and match pages in a PDF to create a new document.