自定义类写入文件

 //对自定义类归档

Person.h  遵守<NSCoding>协议

#import <Foundation/Foundation.h>
@class Book;
@interface Person : NSObject<NSCoding>
@property(copy,nonatomic)NSString *name;
@property(copy,nonatomic)NSString *sex;
@property(strong,nonatomic)Book *book;
@end

Person.m

#import "Person.h"
@implementation Person

-(void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeObject:self.sex forKey:@"sex"];
    [aCoder encodeObject:self.book forKey:@"book"];
}
-(id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super init];
    if (self) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.sex = [aDecoder decodeObjectForKey:@"sex"];
        self.book = [aDecoder decodeObjectForKey:@"book"];
    }
    return self;
}
@end

----------------------写入文件-----------------

创建对象

    Book *book1 = [[Book alloc] init];
    book1.name = @"西游记";
    //写入自定义类
    Person *p1 = [[Person alloc] init];
    Person *p2 = [[Person alloc] init];
    Person *p3 = [[Person alloc] init];
    p1.name = @"wyj1";
    p1.sex = @"男1";
    p1.book = book1;
用archive归档
    NSMutableData *data = [NSMutableData data];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:p1 forKey:@"person"];
    [archiver finishEncoding];

获取文件路径

NSString *doucment = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    doucment = [doucment stringByAppendingString:@"/save"];
将data写入文件
[data writeToFile:doucment atomically:YES];

--------------自定义类对象从文件读取--------------

1.先获取路径

NSString *doucment = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    doucment = [doucment stringByAppendingString:@"/save"];

NSData *data = [NSData dataWithContentsOfFile:doucment];

2.将NSData通过反归档，转化为Personz对象

NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];

3.通过反归档得到复杂对象

Person *p = [unarchiver decodeObjectForKey:@"person"];

[unarchiver finishDecoding];