NSCoding.md

NSCoding

Protocol for object serialization and deserialization in mulle-objc.

Required Methods

• -encodeWithCoder: - Encode object state to coder
• -initWithCoder: - Initialize object from encoded data

Optional Methods

Class Support

• -classForCoder - Returns class used for coding (usually provided by NSObject)
• -decodeWithCoder: - Used by class clusters to decode after instance substitution

Value Encoding/Decoding

• -encodeValueOfObjCType:at: - Encode value of given type
• -decodeValueOfObjCType:at: - Decode value of given type
• -decodeBytesWithReturnedLength: - Decode raw bytes
• -encodeBytes:length: - Encode raw bytes
• -encodeObject: - Encode an object
• -decodeObject - Decode an object

Important Notes

1. For class clusters:

   • Must decode during decodeWithCoder:
   • Substitute instance in -initWithCoder
   • Only look at pure data in -initWithCoder, not references
   • Example: NSData can do all in -initWithCoder:, NSArray cannot

2. Future planned feature:

   • -encodeDecodeWithCoder: - Combined encode/decode method to reduce duplicate code