I have successfully created a Custom Keyboard with Swift on iOS 8 simulator. Although it worked well, but I could not debug it. It is a contained target and was installed through Settings->General. Placing a bookmark in XCode not work.

I am able to debug a custom keyboard using the simulator via Xcode 6. <ol> <li>Select the keyboard (and not it's container) as the scheme. <img src="https://i.stack.imgur.com/rV7K5.png" alt="Change scheme"></li> <li>"Run" and then select on of the apps on your simulator to debug the extension with. </li> </ol> <img src="https://i.stack.imgur.com/3vB0D.png" alt="Run your app">