@interface XXModel : NSObject <NSCoding> {
}
- (void)encodeWithCoder:(NSCoder *)encoder;
- (id)initWithCoder:(NSCoder *)decoder;
@end
继承XXModel，避免每次用到NSCoding都去写NSCoding两个实现。具体实现用Ivar* ivars = class_copyIvarList(cls, &numberOfIvars);
perfect。
原文：http://www.cnblogs.com/backag/p/3584921.html