Say I'm creating a new calendar entry. I type a lot of information, then I get to save or cancel. Technically, cancel is safe because I'm not messing up my existing calendar. But all the typing I did (especially on mobile) would be lost. So is cancel really safe? But Stop wouldn't the right choice either...
What do you suggest?
No, it's not safe in that scenario. "Destructive" means throwing away anything, even one word the user typed. Do not use the word "cancel" for that operation - use the word "Discard" or an X button, with an are-you-sure prompt that has a cancel button that safely brings you back to the editing interface.
Edit: OK, maybe "one word" is an exaggeration. Certainly for the case of a form of input fields a no-prompt cancel button is inappropriate. However, if you have a simple OK/Cancel dialogue that contains a single one-line input field, it is usually acceptable to have a Cancel button that throws away your input without prompting.
(This is the three-button close prompt that's been the standard in desktop operating systems since at least the Windows 3.1 era, but I guess we have to rediscover these things when the same problems come up on mobile.)
They both then show a ‘discard/keep editing’ prompt, but only fantastical has the extra option of a draft.
But in addition to that — fantastical’s popup isn’t even modal. You can push the sheet down to see and interact with the main calendar.
Unfortunately, fantastical doesn’t show the ‘drag handle’ that Mail and other apps use to show this functionality, so it’s not particularly discoverable.