How to parse base64 image from JSON - objective-c

Question

What's the reason that I can't parse a base64 string from a JSON request? when I make it a small string it works.
To clarify a little:
else if([connection isEqual:self.appearanceConnection]){
NSArray *arrayOfAppearances = [NSJSONSerialization JSONObjectWithData:[[[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding] dataUsingEncoding:NSUTF8StringEncoding]options:NSJSONReadingAllowFragments error:&error];
NSLog(#"het aantal appearances is: %i", arrayOfAppearances.count);
[self syncAppearances:arrayOfAppearances];
}
When I edit it to a small string, I get the response that the length of the received array is 1. If I change it again to the base 64 of the image, the length is 0.
http://cl.ly/image/470Z0X1P3K1b (image form JSON response)
The error I get on the String:

Answer 1

Updated answer:
You now inform us that JSONObjectWithData is reporting an error:
Unterminated string around character 62
Character 62 is the start of the logo. I'm not seeing the end of the JSON in any of your screen snapshots. It looks like it's getting cut off.
You haven't shown us how you are populating data, but it looks almost like you're using a NSURLConnection but trying to parse in didReceiveData as opposed to waiting for the full results and only invoking the the JSON parse in connectionDidFinishLoading. NSURLConnection will break a long response into several calls to didReceiveData and you have to append all of those NSData to a single NSMutableData, and only try to parse it when it's done retrieving everything.
You either need to (a) show us the code where you're loading data and/or (b) share the full JSON. Either your JSON isn't properly terminated or you're trying to parse it before the whole thing is downloaded (probably the latter).
Original answer:
I'm not sure if this is the problem, but your line that says:
NSArray *arrayOfAppearances = [NSJSONSerialization JSONObjectWithData:[[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] dataUsingEncoding:NSUTF8StringEncoding]options:NSJSONReadingAllowFragments error:&error];
should simply be:
NSArray *arrayOfAppearances = [NSJSONSerialization JSONObjectWithData:data
options:0
error:&error];
The JSONObjectWithData method takes a NSData, not a NSString.
And, if you're not getting anything returned from this method, you should examine the contents of error and see what it says.
If you're still unable to figure out what the problem is, perhaps you can share the full JSON response with us (give us a URL or upload it somewhere) and we can take a look at it.

Answer 2

With a big thanks to #Rob!
Here a little summary:
Create a variable NSMutableData (don't forget to initialise in the viewdidload)
In the didReceiveData, you append the data to your mutable data using [self.appearancedata appendData:data];
In the connectionDidFinishLoading you parse your JSON