After some more work, I've found that this can be accomplished with mixed success.
Run the app from Xcode to install it on your device and then stop it from Xcode.
Force quit the app from the app switcher UI on the device.
Navigate to the scheme for the project in Xcode. Under the Run section's Info tab, there is a radio button for "Wait for executable to be launched". Make sure this is checked instead of the "Automatically" option.
Run the app from Xcode. It will not open on the device, but the debugger will wait for it to open and then it will attach to it.
So, while the debugger is waiting, you can open an app like Notes where you have a deep link and touch the link to cause the app to open. If you have breakpoints set somewhere, like in application:didFinishLaunchingWithOptions:, you can follow the startup process.
Issues I've found so far:
- NSLog statements do not output to the console, so if you didn't have any breakpoints set, it would appear as though the debugger had not attached to the app at all.
- It has a high probability of causing issues on my device. At one point, the screen would not turn on although all other indicators showed the device was on and accessible (iTunes picked it up right away, my Apple Watch indicated it was still connected, Xcode still indicated it was connected). The screen would not turn on until after a hard reboot. In another case, Notes became unresponsive. So for now, it seems best to do one round of testing and then reboot the device.
