Capturing a Screenshot on a Device
Capture a screenshot on a device connected to your Mac to create launch images for your app.
Connect your device to your Mac.
On the device, configure the screen the way you want to capture it.
In the Devices window under Devices, select your device and click the Take Screenshot button.
The new screenshot appears on the desktop.
When generating your app’s launch images, always capture images from devices with the appropriate screen size and resolution. For a universal iOS app, this means capturing screenshots both from an iPad and from an iPhone or iPod touch. If your app supports the Retina display, also capture screenshots from these devices. If you are submitting your app to the store, capture all required screenshots that you upload later to iTunes Connect, described in iTunes Connect App Properties in iTunes Connect Developer Guide.