Demonstration of uint64 accuracy bug in NSJSONSerialization

gistfile1.m

NSString *jsonString = @"{\"myNumber\":1029742590268606522}";
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];

NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:NULL];
NSLog(@"jsonDict: %@", jsonDict);

uint64_t myNumber = [jsonDict[@"myNumber"] unsignedLongLongValue];
NSLog(@"myNumber: %llu", myNumber);

/*

Output:

2014-02-12 14:47:54.850 Untitled 11[94676:507] jsonDict: {
    myNumber = 1029742590268606522;
}
2014-02-12 14:47:54.852 Untitled 11[94676:507] myNumber: 1029742590268606464


Explanation:

NSJSONSerialization is inappropriately using NSDecimalNumber instead of a standard long long
unsigned NSNumber, and NSDecimalNumber has a bug where getting very large integers out of an
NSDecimalNumber loses accuracy since it uses .doubleValue as in interim representation
(http://stackoverflow.com/a/6713550/86046).

*/