Just seen that the newest version of iThoughts X (an iPad Pro favourite) has the ability to import Scapples, but doesn’t mention any details. I shall try this out just as soon as I can and report back …
It works - just the one way, but it’s not a bad destination if - as sometimes happens here - I start a Scap that takes on a life of its own and needs a few more features.
I use iThoughts when I have to. But I wish there was a Scapple for iPad. It’s my preferred brainstorming and idea sketching tool. Clean, direct, elegant, with no added embellishments. Maybe with Keith now playing on his new iPad Pro…
Paolo
After the launch of Scrivener for Mac 3? 
Since we don’t know if there’s going to exist a version of Scapple for iOS, maybe you should take a look to a little app called Grafio 3. Its shape recognition feature makes it quite attractive and easy to use. You just draw a circle or a rectangle, and it automatically transforms it into a perfect figure. It’s clean, not as structured as iThoughts, but it has all the usual tools to make flowchart, mindmap, and diagram drawing easy, such as connecting figures easily and moving them in groups (something I truly wish Scapple had). It’s cheap already, but it’s half price this weekend. There’s a Lite version, if you want to try it first.
I use MindNode. It’s cross-platform, meaning it seamlessly syncs via iCloud, and there are iOS and OSX versions available. You can write, rearrange, insert notes and images.
Thank you, cor_stellae, for pointing me towards Grafio. It looks really excellent!
Paolo
Reply to the above comment about MindNode, iThoughts also syncs between iOS and Mac versions, via iCloud. There’s a single iOS version for iPhone and iPad.
As well as mindmapping, I use iThoughts to “mindsweep” - a Getting Things Done technique for figuring out all the things you have to do, in a 2 dimensional manner rather than a linear list. Items on the mindmap can be sent to the Mac / iOS Reminders apps and from there they could be automatically ingested by a traditional task manager such as Things or Omnifocus.
I use Scapple when I need to do a diagram that has no constraints. I too wish it was on iOS 
- after Scrivener for iOS.
And you can export from iThoughts to OPML and make it a Scrivener binder structure.
Good to know Scapple can go to iThoughts, I’ll certainly make use of that.
iThoughts for iPad looks good but then I explored the Mac version for syncing purposes. £40 is hardly competitive pricing given the crowded market. 
No, I didn’t buy that either. Very expensive. I only use it on the iPad. On the Mac I use Scapple for stuff like that.