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Base64 encode iOS not returning what I expect

Posted on 2012-03-23
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Last Modified: 2016-02-10
I'm trying to base64 encrypt an image for upload on iOS, but the stupid thing doesn't have built in support, so I downloaded two libraries and tried them both out, but I think they are returning the wrong values (unless I understand base64 even less than I think I do).  This website returns a long string that starts with this:  

/9j/4Q+zRXhpZgAASUkqAAgAAAAKAA4BAgAgAAAAhgAAAA8BAgAFAAAApgAAABABAgAKAA

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When I encrypt using the library I downloaded, it starts with this:

iVBORw0KGgoAAAANSUhEUgAAAI0AAABnCAIAAACy41YWAABAAElEQVR4AbzdeaylyXUY9nf3

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I am 100% sure the first one is correct, because when I use a test program that was written to test the server, that's the same code that it uploads to the server and the server happily decodes the file and saves the image. Here is the test image.

Basically, what I'm thinking is that I need to get a different library for the iPhone / iPad. Another odd thing I noticed is that for some images, the = will be at the end of the string, and for others it won't be. There are three reasons I can think of for this.

1) the iPhone is running out of memory and doesn't want to tell me so it just uploads what it has.

2) the library is broken

3) I'm confused and don't understand base64

Any suggestions?

EDIT: The iPhone is actually the simulator, so I don't know if it will run out of memory before the computer does. I know the android emulator doesn't, but I'm not sure about the iOS simulator.
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Question by:Curtis Long
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Accepted Solution

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pgnatyuk earned 2000 total points
ID: 37760091
I cannot give you my code.

The shortest working code is here:
http://www.cocoadev.com/index.pl?BaseSixtyFour

In Github you can find a longer solution:
https://github.com/mikeho/QSUtilities

or NSData category:
https://github.com/mattgemmell/MGTwitterEngine/blob/master/NSData+Base64.h
https://github.com/mattgemmell/MGTwitterEngine/blob/master/NSData+Base64.m

I found this blog post with the attached code and examples:
iPhone SDK base64 encode / decode
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Author Closing Comment

by:Curtis Long
ID: 37766608
No matter which library I used I would have run into the same thing. I was telling it to use a png image as a representation even though the image was a jpeg, which was what was causing the different values for base64, which makes a lot of sense.
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