Capturing a Screenshot on an iOS Device
Capture a screenshot on your device to document your progress during development and to create launch images for your iOS apps.
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 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 App Store, capture all required screenshots that you upload later to iTunes Connect, described in iTunes Connect App Properties in iTunes Connect Developer Guide.