NSCoding协议 与NSCoder类、NSKeyedArchiver类

1、NSCoding协议使用.

//遵循NSCoding协议
@interface HYCoding : NSObject <NSCoding>      
@property (nonatomic, strong) NSString *name;    
@property (nonatomic, strong) NSString *hobby;    
@end    

//encode 属性
-(void)encodeWithCoder:(NSCoder *)coder  
{  
    [coder encodeObject:self.name forKey:@"name"];  
    [coder encodeObject:self.hobby forKey:@"hobby"];  
}  

//decode属性
-(instancetype)initWithCoder:(NSCoder *)coder  
{  
    self = [super init];  
    if (self) {  
        self.name = [coder decodeObjectForKey:@"name"];  
        self.hobby = [coder decodeObjectForKey:@"hobby"];  
    }  
    return self;  
}  

//测试
+(void)testCoding{  
    HYCoding *coding = [[HYCoding alloc] init];  
    coding.name = @"sds";  
    coding.hobby = @"sdds";  
    HYCoding *coding1 = [[HYCoding alloc] init];  
    coding1.name = @"sds";  
    coding1.hobby = @"sdds";  
    NSArray *array = [NSArray arrayWithObjects:coding,coding1, nil];  
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array requiringSecureCoding:YES error:nil];  
    NSArray *array_unarchiver = [NSKeyedUnarchiver unarchiveObjectWithData:data];  
}

2、 NSCoder类、NSKeyedArchiver类 内部如何实现的呢？