I am developing one application. In that I want to save my pictures in camera roll. So how to save my pictures in camera roll through code?
The most basic way (and the only way if you're targeting iOS before 4.0) is to use UIImageWriteToSavedPhotosAlbum. This lets you specify a selector to be called on a target object when the save is complete.
In 4.0, you can use ALAssetsLibrary's writeImageToSavedPhotosAlbum:orientation:completionBlock: to write the image; in this case, you provide a block to be called when the save is complete.
In 4.1, you can also use ALAssetsLibrary's writeImageDataToSavedPhotosAlbum:metadata:completionBlock: or writeImageToSavedPhotosAlbum:metadata:completionBlock: to write an image along with metadata (e.g. geotagging information). The former is also the only way to write an image from an NSData object without first loading it as a UIImage or CGImageRef.