I came to the same thing as @mattgallagher independently. For me it was extremely slow to debug. Step over took up to 10 seconds as well as loading current variables. So, after some investigation, I realised that Xcode, after it first discovered your device by WiFi, continue use WiFi even if it's connected by cable. Solution which worked for me: Unpair device in the "Device and Simulators" window. Connect usb cable to device. Start debugging. You have to repeat this every time after you disconnect the cable. Go to airplane mode on device. Connect the cable. Switch off the airplane mode. Start debugging. You have to repeat this every time after you disconnect the cable.