How to use NSCoder

Question

I am developing iphone application.

I use NSCoder.

MyApplication.h

#define ITEMS_KEY @\"items\"
#define CATEGORIES_KEY @\"categories\"


#imp         


        

Answer 1

Here is the NSCoding protocal methods from my LogEntry object, you can ignore the switch statement and the schema details though, those are from a base class I have written that allows me to keep sane track of changing data formats.

Please note that in addition to using decodeObjectForKey: you also need to make sure you retain/copy the given values as they are autoreleased when received.

- (id)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];

    if (self != nil) {
        switch ([schemaVersion intValue]) {
            case 2:
                filepath = [[coder decodeObjectForKey:@"filepath"] copy];
                identifier = [coder decodeInt64ForKey:@"identifier"];
                level = [coder decodeIntForKey:@"level"];
                lineNumber = [[coder decodeObjectForKey:@"lineNumber"] retain];
                message = [[coder decodeObjectForKey:@"message"] retain];
                timestamp = [[coder decodeObjectForKey:@"timestamp"] retain];
                break;              
            default:
                [self release], self = nil;
                break;
        }
    }

    return self;
}

- (void)encodeWithCoder:(NSCoder *)coder {
    [coder encodeObject:filepath forKey:@"filepath"];
    [coder encodeInt64:identifier forKey:@"identifier"];
    [coder encodeInt:level forKey:@"level"];
    [coder encodeObject:lineNumber forKey:@"lineNumber"];
    [coder encodeObject:message forKey:@"message"];
    [coder encodeObject:timestamp forKey:@"timestamp"];

    [super encodeWithCoder:coder];
}