Recently, there have been more compilation warnings in the project after the upgrade, which looks annoying, so I wanted to fix them. I started with the warning "Debug warning: Mapping architecture armv7 to i386".
After looking at the warning, I realized that it was related to the architecture setting in the Build Settings of the corresponding target. So I checked the Valid Architectures of the today widget and iwatch widget under the corresponding target and found that they were inconsistent between Release and Debug. Then I manually changed it to $(ARCHS_STANDARD), compiled it, and it was done. The issue was perfectly resolved.