You could look into UIImagePickerController
should only take a short time to implement and easy to get the image the user picks but you cannot change the appearance or extend the functionality.
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIImagePickerController_Class/
EDIT: Due to my misunderstanding.
This GitHub has a very good and easy solution for simply displaying an image in a full screen manner with built in gesture control.
https://github.com/bufferapp/buffer-ios-image-viewer
One of the best parts is that you can initialise it with URL/ALAsset/PHAsset/UIImage all through the same initialiser.
BFRImageViewController *imageVC = [[BFRImageViewController alloc] initWithImageSource:@[image]];
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solved Display picture in gallery [closed]