Photogene is the a Nice tool for handling your iPhone photos. It’s a full featured photo editor.
It has Powerful collage maker and it also Supports uploading multiple photos.

Photogene App

Photogene App

Check out some Main features below:

  • Full featured photo editor: crop, straighten, color adjustments (including histogram and curves), sharpen and denoise, retouch tools (dodge/burn, heal, localized effects and more).
  • Export several photos at once. Photogene supports a wide selection of export destinations, including Flickr, Dropbox, Facebook, Twitter, Picasa, FTP and e-mail.
  • Full support for iPhone 4S native 8 MP resolution.
  • Special effects: center focus, vignette, frames, reflection, text boxes and much more.
  • Presets: large collection of predefined presets. Instantly give your photo a new look and then tweak it yourself.
  • Collage maker: combine several photos into one piece of art using a variety of templates.
  • Camera: use our built-in camera module to snap great photos and apply real-time effects.
  • Metadata viewer: visual display of all the information stored in your photos. Including location on a map, date&time, file size, etc (IPTC editor included).
  • Resize your photos as you export them. You can export edited photos at full resolution (same as the original).
  • Compare edited photo vs the original at any time.

The app is provided in appstore for 0.99$.Worth a try.

Source : Appstore link