Help with simple EncodeObject & DecodeObject
Help with simple EncodeObject & DecodeObject
- Subject: Help with simple EncodeObject & DecodeObject
- From: email@hidden
- Date: Tue, 28 May 2002 01:16:26 EDT
I admit it, I am having problems with the simplest of Cocoa document tasks, saving and opening data file.
What is the difference between using decodeObject/encodeObject and the various other flavors of the call (decodeDataObject, decodeRootObject, decodeNXObject, etc.)?
I have a simple document that contains a number of integers and strings (stored internally as NSString & NSNumber). To implement dataRepresentationOfType, I use NSArchiver and encode Object thus:
NSMutableData *a_data = nil;
NSArchiver *a_archiver = [[[NSArchiver alloc] initForWritingWithMutableData: [NSMutableData data]] autorelease];
if (a_archiver) {
[a_archiver encodeObject:someStr];
[a_archiver encodeObject:someNumber];
a_data = [a_archiver archiverData];
}
return a_data;
To implement loadDataRepresentation, I am using NSUnarchiver, decodeObject, and some already created Set methods:
if (data) {
NSUnarchiver *a_unarchiver = [NSUnarchiver unarchiveObjectWith
Data:data];
if (a_unarchiver) {
NSString* a_str = [a_unarchiver decodeObject];
NSNumber* a_number = [a_unarchiver decodeObject];
if ([a_unarchiver isAtEnd]) {
[self setMyString: a_str]
[self setMyNumber: a_number];
return YES;
}
}
}
return NO;
When I save, it seems to work, but when I read, I get various errors:
2002-05-28 01:11:48.605 d20 Edit[1278] *** +[NSUnarchiver unarchiveObjectWith
Data:]: extra data discarded
2002-05-28 01:11:48.611 d20 Edit[1278] *** -[NSshortNumber decodeObject]: selector not recognized
2002-05-28 01:11:48.651 d20 Edit[1278] *** -[NSshortNumber decodeObject]: selector not recognized
What am I doing wrong? Does anyone have source code examples of saving simple structures. Notice the data is NOT in a collections nor an array (I do not want to store it that way for a number of internal reasons). I thought the archivers/unarchivers were supposed to store the encoded information into a data object, to be passed to & from the file IO. I do not want to store the internal format of the object (ie. information regarding what type of object it is). I just want to store the internal data (the bytes of number or text).
Any ideas what I am missing?
Thanks!
Steve
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