You can edit photos right on iPhone. While viewing a photo full-screen, tap Edit, then tap one of the tools.
Drag the photo to reposition it, then tap Crop.
Don't like the results? Tap the tool again to return to the original.
Trim a video. Tap the screen to display the controls, drag either end of the frame viewer, then tap Trim.
Set the Slo-Mo section of a video. (iPhone 5s) Use the vertical bars beneath the frame viewer to set the section of the video you want to play in slow motion.