Thanks a lot. I misunderstood role of drawRect: method. I will resolve the problem with your advice. Thanks again. Best Regards, Tetsuya

I’m sorry but I can’t read your post. Please put it in a reply rather than the comments, and also attach the full crash report. See Posting a Crash Report for advice on the latter. I apologize to post an unreadable comment. Thanks for your reply. I ran the app on my m1-mac. the product resides on maccatalyst folder, I thinks it's native. (the icon shows no "no-enter" sign) I checked the crash log. It shows that some infinite recursive call exists. On iOS, I have no such a phenomenon, it may caused by difference of sublayer between macOS and iOS.  crash.log