Two things worth mentioning about view debugging:
a) Yes, there is a setting in Xcode to enable/disable view debugging per scheme. Edit your current scheme (Product > Scheme > Edit Scheme...) and check the 'Run > Options' section.

b) Even in Xcode 6.1 (6A1052d), two prerequisites need to be fulfilled for view debugging to work (at least in my experience):
- App needs to be running on a 32 bit device (iPhone 5 or older)
- App needs to be running on iOS 8 or newer
View debugging worked for me on both, actual devices and in the simulator (although it works more reliable for me on the simulator).