IPhone, how to read image from photo library like NSData?

Question

On iPhone, I saved the image in the photo library with the changes (adding data after the image code) using the assest library to save the NSData directly in the photo library. Now I want to read the image from the photo library as NSData in order to read it. If I read it as a UIImage, it will change the data inside the image.

How can I read a photo from a photo library like NSData? I tried to look at the link url in 4.1 but no luck.

Edit: I edited to explain why I save it as NSData. The URL method in the answers works if you just need pure NSData but it doesn’t help in the context that I am asking for.

Edit 2: The answer with getBytes was the answer that did this for me. The code I used was:

int8_t *bytes = malloc([representation size]); NSUInteger length = [representation getBytes:bytes fromOffset:0 length:[representation size] error:&error]; 

This allowed me to get everything inside the file that gave me the PLUS image code, which I added in the form of NSData.

Edit 3:

Is there a way to do this now in iOS 10 using PHPhotoLibrary, which replaces AssetLibrary? I need the image in NSData to be the original RAW image without any changes.

Answer 1

You should learn the getBytes method for ALAssetRepresentation. This gives you the raw RAW image data of your image, and also allows you to use a buffer to process the image instead of reading the image into memory at the same time. And, of course, you can always generate NSData from the getBytes method.

Greetings

Hendrick

Answer 2

If you already have ALAsset , you can get the default NSData views using the following:

 NSData *data = [NSData dataWithContentsOfURL:[[asset defaultRepresentation] url]];