Keyboard shortcut to switch to specific app in OS X

Solution 1:

Have you tried using Snap from the App Store?

FEATURES:
Snap automatically assigns keyboard shortcuts to apps pinned in your dock using a modifier key (command, option, control, or shift) and the number keys. For example, command+1 opens the 1st app in your dock, command+2 the 2nd, etc. Rearrange or add new apps to the dock and the shortcuts will automatically reset.