//文件路径
-(NSString *)cachesTestPathWithFileName:(NSString *)fileName{
    NSString * homePath=NSHomeDirectory();
    NSString * libraryPath=[homePath stringByAppendingPathComponent:@"Library"];
    NSString * cachesPath=[libraryPath stringByAppendingPathComponent:@"Caches"];
    return [cachesPath stringByAppendingPathComponent:fileName];
}

// 1. 单个对象的归档解档
    NSArray * arr=@[@"hello"];
    //获取归档路径
    NSString * keyPath=[self cachesTestPathWithFileName:@"arr.key"];
    //执行归档操作
    BOOL rel=[NSKeyedArchiver archiveRootObject:arr toFile:keyPath];
    if (rel) {
        NSLog(@"完成");
    }
    //执行解档操作
    NSArray * arrOut=[NSKeyedUnarchiver unarchiveObjectWithFile:keyPath];

// 2.多个对象归档到一个文件中
    //用于存储归档进的对象数据。
    NSMutableData * data=[[NSMutableData alloc]init];
    //实例化归档对象
    NSKeyedArchiver * keyedArchiver=[[NSKeyedArchiver alloc]initForWritingWithMutableData:data];
    //开始归档多个对象
    [keyedArchiver encodeObject:@{@"a":@"b"} forKey:@"dic"];
    [keyedArchiver encodeDouble:1.414 forKey:@"gen2"];
    [keyedArchiver encodeBool:YES forKey:@"bool"];
    [keyedArchiver finishEncoding];
    //把存储归档数据的data保存到本地
    NSString * theDataPath=[self cachesTestPathWithFileName:@"save"];
    [data writeToFile:theDataPath atomically:NO];
    
    //多对象解档
    NSData * outData=[NSData dataWithContentsOfFile:theDataPath];
    //创建解档对象
    NSKeyedUnarchiver * unArchiver=[[NSKeyedUnarchiver alloc]initForReadingWithData:outData];
    NSDictionary * outDic=[unArchiver decodeObjectForKey:@"dic"];
    NSLog(@"%@",outDic);
    NSLog(@"%f",[unArchiver decodeDoubleForKey:@"gen2"]);

在 .h 文件中
//自定义类，想要实现归档接档，要遵守NSCoding协议
@interface Student : NSObject
<NSCoding>

@property (nonatomic,copy) NSString * name;
@property (nonatomic) float score;

@end

在 .m 文件中
//实现归档协议方法
-(void)encodeWithCoder:(NSCoder *)aCoder{
    //对属性进行归档操作
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeFloat:self.score forKey:@"score"];
}

//实现解档协议方法
-(instancetype)initWithCoder:(NSCoder *)aDecoder{
    if (self=[super init]) {
        //把自身属性重新赋值。
        self.name=[aDecoder decodeObjectForKey:@"name"];
        self.score=[aDecoder decodeFloatForKey:@"score"];
    }
    return self;
}

@end

//  3. 实现自定义类的归档和解档
    Student * stu=[[Student alloc]init];
    stu.name=@"小明";
    stu.score=80;
    //归档
    NSString * stuPath=[self cachesTestPathWithFileName:@"stu.key"];
    [NSKeyedArchiver archiveRootObject:stu toFile:stuPath];
    //解档
    Student * outStu=[NSKeyedUnarchiver unarchiveObjectWithFile:stuPath];
    NSLog(@"%@ %f",outStu.name,outStu.score);