OC-归档（序列化）(了解的不多没细看)

IOS的本地存储：plist属性列表(Property List)，归档，sqlite，coredata

什么是归档

归档就是将对象打包成二进制序列

归档的作用

归档可以将程序中使用的多个对象及其属性值，以及他们的相互关系保存到文件中或者发送给另一个进程
简单点说就是将对象以对象的形式存储在文件中并且还可以以对象的形式从文件中拿出来

够可以将相互关联的多个对象归档为二进制文件，

NSCoding协议

归档需要先引入协议

@protovol NSCoding
-(void)encodeWithCoder:(NSCoder*)aCoder;
-(id)initWithCoder:(NSCoder*)aDecoder;
@end
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NSCoder 是一个抽象类 NSKeyedArchiver和NSKeyedUnarchiver是NSCoder的子类
NSCoder就相当于一个二进制空间
NSCoder的实例成为归档器

-(void)encodeWithCoder:(NSCoder*)aCode//指定对象归档规则

-(void)encodeWithCoder:(NSCoder*)aCode
{
	//如果父类适用于NSCoding协议 则super也需要调用 
	//[super encoderWithCoder:aCoder];
	[coder encodeObject:/*归档变量*/ forKey:/*归档名称*/];
	[coder encodeObject:self.name forKey:@"name"];
}
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-(id)initWithCoder:(NSCoder*)aDecoder//指定对象解档规则

//如果父类适用NSCoding协议 则
//self = [super initWithCoder:aDecoder];
//如果父类不适用则调用
//self = [super init];
接收变量 = [coder decodeObjectForKey:/*归档名称*/];
self.name = [coder decodeObjectForKey:@"name"];
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NSKeyedArchiver archiveRootObject:toFile: //对目标对象进行归档

[NSKeyedArchiver archiveRootObject:归档对象 toFile:归档目标路径]
[NSKeyedArchiver archiveRootObject:a toFile:@"/Users/RenkaiYang/Desktop/archive/test.txt"]
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NSKeyedUnarchiver unarchiveObjectWithFile://通过解档目标文件初始化对象

A *a = [NSKeyedUnarchiver unarchiveObjectWithFile:目标文件路径];
A *a = [NSKeyedUnarchiver unarchiveObjectWithFile:@"/Users/RenkaiYang/Desktop/archive/test.txt"];
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(id) initForWritingwithMutableData:(NSMutableData*)data

多对象的
将预先生成的NSMuable实例作为参数初始化NSkeyedArchiver实例这个data的数据会被保留最后作为归档

NSMutableData *data = [NSMutableData data];//创建一个data对象
//根据二进制流创建NSKeyedArchiver对象
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];
//感觉可能是将在archiver和data之间创建一个二进制流
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[archiver encodeObject:a forKey:@“a”];
[archiver encodeObject:aa forKey:@“aa”];

实例

dog.h

@interface Dog : NSObject<NSCoding>
@property (nonatomic,copy)NSString* name;
@end
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dog.m

#import "dog.h"

@implementation Dog
-(void)encodeWithCoder:(NSCoder *)coder
{
    [coder encodeObject:self.name forKey:@"name"];
}
-(nullable instancetype)initWithCoder:(NSCoder *)coder
{
    if(self = [super init])
    {
        self.name = [coder decodeObjectForKey:@"name"];
    }
    return self;
}
@end

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main.m

//
//  main.m
//  OCTest
//
//  Created by Renkai Yang on 2022/7/26.
//

#import <Foundation/Foundation.h>
#import "dog.h"
@interface A:NSObject<NSCoding>
@property (nonatomic,copy)NSString *name;
@property (nonatomic,assign)int age;
@property (nonatomic,assign)double weight;
@property (nonatomic,strong)Dog*dog;
@end
@implementation A
-(void)encodeWithCoder:(NSCoder *)coder//设定归档规则
{
    [coder encodeObject:self.name forKey:@"name"];
    [coder encodeInt:self.age forKey:@"age"];
    [coder encodeDouble:self.weight forKey:@"weight"];
    [coder encodeObject:self.dog forKey:@"dog"];//如果要给自定义类归档解档 就需要在自定义类中制定归档解档规则
}
-(nullable instancetype)initWithCoder:(NSCoder *)coder//设定解挡规则
{
    if(self = [super init])//这里要初始化主要是用来给新对象初始化
    {
        self.name = [coder decodeObjectForKey:@"name"];
        self.age = [coder decodeIntForKey:@"age"];
        self.weight = [coder decodeDoubleForKey:@"weight"];
        self.dog = [coder decodeObjectForKey:@"dog"];
    }
    return self;
}
@end
void test()//进行归档操作
{
    A *a = [[A alloc]init];
    a.name = @"Yang";
    a.age = 23;
    a.weight = 58.0;
    a.dog = [[Dog alloc]init];
    a.dog.name = @"大黄";
    NSLog(@"归档开始");
    if([NSKeyedArchiver archiveRootObject:a toFile:@"/Users/RenkaiYang/Desktop/archive/test.txt"])//将a对象归档到指定文件中
    {
        NSLog(@"归档成功");
    }
    else
    {
        NSLog(@"归档失败");
    }
}
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        test();
        A *a = [NSKeyedUnarchiver unarchiveObjectWithFile:@"/Users/RenkaiYang/Desktop/archive/test.txt"];//通过解档文件对a进行初始化
        NSLog(@"%@",a.name);
        NSLog(@"%d",a.age);
        NSLog(@"%f",a.weight);
        NSLog(@"%@",a.dog.name);
    }
    return 0;
}

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多对象归档
dog.h

@interface Dog : NSObject<NSCoding>
@property (nonatomic,copy)NSString* name;
@end
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