In the sample project "Drawing with PencilKit", even scrolling by 1 pixel can cause my iPad Pro to use 167% CPU and keep this usage for 2-5 seconds. My iPad got too hot after few minutes that I can't barely put my palm on it.
This a serious problem and could be reprocedure easily:
Run the sample "Drawing with PencilKit" on your iPad
Open the sample note
Select all strokes in the note and duplicate about 7 times (it is just an average number of strokes I write in a page on a note-taking app like GoodNotes).
Scroll and watch the CPU usage jumps in Xcode
It is not matter how long you scroll or how many strokes are visible on the screen. If the drawing has that much strokes, the CoreHandwriting objects will eat all the CPU.
I hope it got fixed soon because it make apps with PencilKit consume too much baterry, getting too hot and we receive many bad review because of it :(
Many thank to Pencil and Paperteam for developing this Framework btw, this framework is awesome, but it could be better, I believe.
TheLich
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After testing iOS16, I've found a serious bug that make all apps with PencilKit (Prodrafts, InDraft, Pencil it in, Paint...) completely useless:
If a canvasView is scrolled, all existing strokes will be shifted while writing with Apple Pencil.
After writing, all strokes will be shifted back to its positions but it make users unable to write anything.
This bug is also occurs in the example app of PencilKit: https://developer.apple.com/documentation/pencilkit/drawing_with_pencilkit
It's easy to reprocedure: Run the example app, open a note, scroll down, then write something. You will see the bug (this bug only happens in iOS 16 and iPadOS 16).
I have sent multiple bug reports since the first days of the beta, none of them are answered. It's been 2 beta versions and the bug has not been fixed yet.
I'm an indie developer and I have worked with my app for 2 years - full time - 12 hours a day - no weekend. The main feature of my app is taking note with Apple Pencil and this bug made my app completely broken. I'm terrifying that 2 years of my work will be wasted.
Please answer me, give me hope. Thank you :(