CODEWITHSUNDEEP
iosfile-iohashalassetslibrary
groomsy
groomsy

Reputation: 4955

Writing Image to ALAssetsLibrary Results in a Different File Hash

I have an application that is downloading images from a server and inserting them into the iPhone's ALAssetsLibrary so that the user can see those images in their saved album. I am trying to do a confirmation by comparing file hashes to ensure the image was downloaded successfully. I have the file hash as the file exists on the server. Once I finish writing the image to the ALAssetsLibrary, I generate a file hash on the client. I'm observing that the file hashes are different but the files appear to be the same. I'm curious as to whether or not the client is altering these images somehow that I may not know about (aspect ratio, scale, metadata, etc). Any guidance, opinions, or advice would be helpful.

Upvotes: 1

Views: 180

Answers (1)

holtmann
holtmann

Reputation: 6303

The image-data itself is not altered during import into the Assets-Library. However, I observed that JPEG files get about 10KB bigger, after they have been imported into the Assets-Library. The Assets-Library seems to add a JFIF-Metadata-Dictionary to the file, if not already present.

Upvotes: 1

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