Limitations of NSMutableData for NSKeyedUnarchiver

I have read on another post (Archiving / Unarchiving results in initForReadingWithData incomprehensible archive) that you can't store more than 250kBytes on a NSMutableArray. Unfortunately, in order to recover such data with NSKeyedUnarchiver, you must use a NSMutableArray. I am trying to get back an image with a size around 500kB.

  MTMessage *message = [NSKeyedUnarchiver unarchiveObjectWithData:data];

The error 开发者_如何学编程I get is :

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKeyedUnarchiver initForReadingWithData:]: incomprehensible archive (0x0, 0x10, 0x4a, 0x46, 0x49, 0x46, 0x0, 0x1)'

Apparently it's a pretty common situation (even-though i have not found a solution yet). Would you have any idea of how to bypass the use of NSMutableData. Thank you.

EDIT : Actually it says that data has a size of 524 288 bytes, which is correct, so the problem might come from the unarchiver.

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NSKeyedArchiver does not depend on an NSArray (immutable or not).

I'm also not aware of a bug correlated with NSKeydArchiver and depending on archive size.

The following code runs fine on Lion:

NSMutableData *data = [NSMutableData data];
for (uint32_t i = 0; i < 1024 * 1024; ++i)
    [data appendBytes:&i length:sizeof(uint32_t)];

NSData *archive = [NSKeyedArchiver archivedDataWithRootObject:[NSMutableArray arrayWithObject:data]];
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:archive];

assert([data isEqual:[array lastObject]]);

Please provide more code for more insight in your actual problem. Are you maybe trying to unarchive an encoded image instead of an archive?