数据持久化

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归档Archiver -> 对数据进行写操作

解档（反归档）Unarchiver - > 对数据进行读操作

总结：

1. 一般不会使用归档 / 解档的方式存储基本数据类型

2. 本质：基本数据类型 <--> NSData

Demo1_NSKeyArchiver

<span style="font-size:14px;"><span style="font-size:14px;">//需求：把NSArray数据使用归档/解档写入并读取    //准备写入的文件路径:/Documents/archiver(文件名)    NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];    NSString *filePath = [documentPath stringByAppendingPathComponent:@"archiver"];    //归档步骤    NSArray *array = @[@"Jack", @19, @[@"Java", @"Swift", @"Ruby"]];    //1.准备一个可变数据类型    NSMutableData  *mutableData = [NSMutableData data];    //2.创建NSKeyedArchiver对象    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:mutableData];    //3.对数据进行编码    [archiver encodeObject:array forKey:@"arrayKey"];    //4.执行完成编码    [archiver finishEncoding];    //5.写入文件    [mutableData writeToFile:filePath atomically:YES];    //归档变相执行如下步骤：NSArray转成NSData写入文件        //解档步骤    //1.从指定的文件读取数据(NSData从文件中读取)    NSData *readData = [NSData dataWithContentsOfFile:filePath];    //2.创建NSKeyedUnarchiver对象    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:readData];    //3.对数据进行解码    NSArray *readArray = [unarchiver decodeObjectForKey:@"arrayKey"];    //4.执行完成解码    [unarchiver finishDecoding];    //5.验证数据    for (id obj in readArray) {        NSLog(@"%@", obj);    }    //解档变相执行的操作：NSData转成NSArray</span></span>

使用归档 / 解档方式存储自定义类型（模型类）

Demo02_Custom

前提：只要是遵循了NSCoding协议的类型

步骤：

1.需要遵守NSCoding协议

2.必须实现协议要求的两个方法（编码 / 解码）

3.针对调用（控制器）接续添加Demo01的几个步骤

<span style="font-size:14px;">NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];    NSString *filePath = [documentPath stringByAppendingPathComponent:@"archiver"];    //准备自定义的模型对象    Student *stu = [Student new];    stu.name = @"Maggie";    stu.age = 20;    //归档    NSMutableData *mutableData = [NSMutableData data];    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:mutableData];    [archiver encodeObject:stu forKey:@"stuKey"];    [archiver finishEncoding];    [mutableData writeToFile:filePath atomically:YES];        //解档    NSData *readData = [NSData dataWithContentsOfFile:filePath];;    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:readData];    Student *readStu = [unarchiver decodeObjectForKey:@"stuKey"];    [unarchiver finishDecoding];        //验证数据    NSLog(@"name:%@; age:%d", readStu.name, readStu.age);</span>

Student.h

<span style="font-size:14px;">@interface Student : NSObject<NSCoding>/**姓名*/@property (nonatomic, copy) NSString *name;/**年龄*/@property (nonatomic, assign) int age;@end</span>

Student.m

<span style="font-size:14px;">@implementation Student- (void)encodeWithCoder:(NSCoder *)aCoder{    [aCoder encodeObject:self.name forKey:@"nameKey"];    [aCoder encodeInt:self.age forKey:@"ageKey"];}- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder{    if (self = [super init]) {        self.name = [aDecoder decodeObjectForKey:@"nameKey"];        self.age = [aDecoder decodeObjectForKey:@"ageKey"];    }    return  self;}@end</span>

Demo03_Custom_UserDefault

步骤：

1. 需要遵循协议NSCoding

2. 实现两个方法

3. 需要执行stu -> NSData -> NSUserDefaults转换

<span style="font-size:14px;"><span style="font-size:14px;">//准备自定义的模型对象    Student *stu = [Student new];    stu.name = @"Maggie";    stu.age  = 20;        //NSUserDefaults写    //把Student->NSData    NSData *writeData = [NSKeyedArchiver archivedDataWithRootObject:stu];    [[NSUserDefaults standardUserDefaults] setObject:writeData forKey:@"stuKey"];    [[NSUserDefaults standardUserDefaults] synchronize];        //NSUserDefaults读    NSData *readData = [[NSUserDefaults standardUserDefaults] objectForKey:@"stuKey"];    //NSData -> Student    Student *readStu = [NSKeyedUnarchiver unarchiveObjectWithData:readData];        //验证数据    NSLog(@"name:%@; age:%d", readStu.name, readStu.age);</span></span>

student 类未变

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