Hardware is iPhone 6S+ (chose closest match)
The crafting help menu states 'Press and hold the item in the output slot to craft continuously.' This does not seem to work in either the classic or pocket interfaces.
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Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-28689.
Please add a vote and any new information to the main ticket, which will be updated accordingly.
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Thank you! Searched but for some reason did not find that. Voted for the original.

Thank you! Searched but for some reason did not find that. Voted for the original.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-28689.
Please add a vote and any new information to the main ticket, which will be updated accordingly.
If you have not, you might like to make use of the search feature before making a new ticket, as it's likely that the issue has been reported already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki