When your iOS device or simulator stuck on a splash screen.

In a circumstances, when you tried to debug your app on an iOS device or simulator, your splash screen could be not passed and your app is just stuck on that screen.

Even you reinstall the app, it does not be fixed.

Here is a solution.

Delete ‘DeviceSupport’ or retry a pairing your device.

Slow app launch time after updating to iOS 14 and Xcode 12

Or you couldn’t resolve with above, try it.

Xcode 11 hangs while attaching deb... | Apple Developer Forums

1. Quit Xcode.
2. Open the Mac desktop application Terminal.app.
3. Execute command "rm -rf ~/Library/Developer/Xcode".
4. Open Xcode.
5. Select the Xcode menu "Product - Scheme - Edit Scheme".
6. Check the "debug executable" in "Run - Info"
7. Then I was able to debug.