The Base SDK version number must be greater than or equal to the software version number on your development device; otherwise, Xcode can’t initiate a debugging session with the device. Set the Base SDK for your project and targets to the latest operating system, which is the default value. The Base SDK property is located in the Architectures area in the Build Settings pane. For iOS apps, set Base SDK to Latest iOS. For Mac apps, set Base SDK to Latest OS X. If you select another value, download and install the latest SDK version that’s greater than or equal to your device software version