How to add PosterLabs Frames to UIImage?

Question

My IOS application is same as PosterLabs app (i.e., https://itunes.apple.com/us/app/posterlabs-stylish-collage/id875654777?mt=8) .I should pick multiple images from album and It should save in UIView and when I click a button,all the picked images should parse to next view.If I pick three images after clicking UIButton it should directly go to next view and those 3 images should set to posters with 3 frames.if I Pick 1,2,3,4,5 same process will be followed,Actually my issue is,In gallery I'm able select the images that i needed but how to display picked images in UIView by using scrolling and if I select 3 images how to set them only to 3 frames,if I select 4 how to set them to 4 frames .I'm not getting any idea regarding this.I'm going mad with this.Hope someone helps me.Thanks in advance.