Binary data to string conversion issue

Question

I'm having trouble converting binary data (some text) back to a string.

The original text comes from a JSON feed, and is then convertet into binary data to store (with the correct formatting) in CoreData. My problem is getting it back out of CoreData. When I try to convert it with the following: NSString *howToString = [[NSString alloc]initWithBytes:[dish.dishMainText bytes] length:[dish.dishMainText length] encoding:NSASCIIStringEncoding]; I get the following:

    bplist00‘T$topX$objectsX$versionY$archiver—TrootÄ¢   
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As you can see, in the beginning and in the end there is some text that is not properly converted. I have tried different forms of encoding (UTF, Latin1/2 and so on) but nothing seems to work perfectly. This is the best result I have been able to produce so far, but it's obviously not satisfactory.

Let me know if more code is needed.

Thanks in advance Chris

I use RKEntityMapping (part of RestKit), and then just assign the JSON string to a Binary Data attribute of my entity — Chris, Jun 05 '14 at 12:21
As @GregParker stated. This is an example of how to read it in Apple doc : https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/PropertyLists/ReadWritePlistData/ReadWritePlistData.html#//apple_ref/doc/uid/10000048i-CH8-SW1 — 3329, Jun 05 '14 at 19:10

score 0 · Answer 1 · answered Jun 05 '14 at 19:04

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That bplist00 text at the start of the data suggests that your data is in fact a binary plist, not a simple encoded string. Try using NSPropertyListSerialization to decode your data.

answered Jun 05 '14 at 19:04

Greg Parker

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Thanks for your answer Craig, I'm afraid that didn't give me the desired result either. It returns even more "raw data" – Chris Jun 05 '14 at 20:37

score 0 · Answer 2 · answered Aug 08 '14 at 17:09

This is a keyed archive, which is a sort of subspecialty of property list. It's a serialized object graph from your app. You can unarchive it like this:

id rootObject = [NSKeyedUnarchiver unarchiveObjectWithData:[dish.dishMainText bytes]];

Note that the result -- assuming the data was archived from your app and it's a valid archive -- is an object graph, not a string.

Binary data to string conversion issue

2 Answers2