Easy to use iPhone screen capture (single image)

I'm looking for an app that captures my iPhone screen and saves it as a photo or allows me to save it as a photo using a 3- or 5-second delay like Snip & Sketch does on Windows. Is there such a thing out there? Can you point me in the right direction? I do NOT want to have to press buttons on my iPhone to do screen capture (quickly wears out the buttons). I see apps that do videos of what's on an iphone screen (videos that can then be used to create screen snaps), but that's not what I'm looking for (too much effort, not easy enough). If what I'm looking for is not available, can someone send a suggestion to a capable developer? This would be a very useful app.