Let me share on how I update my WordPress post using my iPad. I’m using basically a couple of purchased photo manipulation apps to create my post images. You can either create an image from scratch, do a screen capture on your iPad or get images from the internet.
The app, WordPress is useful for a start to create a new post and upload your images from your iPad. You can then login to your WordPress account using Safari browser to further edit the posts.
The uploaded images using the app, WordPress can be found under your media library.