Since you have to submit screenshots as part of your Mock App Store Submission, I thought I’d take a moment to detail some techniques for doing so.
If you’re on the iPhone Simulator, the easiest way to take a screenshot of just the screen is to hold down Control and select “Copy Screen” from the “Edit” menu. This can also be accessed by pressing Control-Command-C.
Then, the easiest way to create an image from the clipboard is to open the Preview app (can launch via spotlight) and select “New from Clipboard”.
Then you can simply save the image as a PNG.
There are 2 easy ways to get screen captures from an iPhone OS device — through Xcode or using the iPhone’s built in screen capture utility. I prefer using Xcode as it takes a lossless PNG images, whereas the device seems to capture lossy JPG images.
To capture using Xcode, plug in your device and bring up the Organizer by selecting “Organizer” from the “Window” menu.
Once open, select your iPhone OS device and then select the “Screenhots” tab. To capture a screenshot, simply press the “Capture” button and the most recent screenshot taken will be displayed in the right panel and all screenshots will appear in the left panel. Though not obvious, you can easily save any image on the left by simply dragging it out of Xcode’s Organizer into a Finder window.
To capture using the iPhone’s built in screen capture utility simply hold the home button and press the sleep/wake button. You should see an on-screen flash when a capture is taken. The screenshot will then appear in an album in your Photos app, which you can then email or sync off of the device.