iOS 归档解档的使用

• 利用OC提供的解归档来实现自定义模型缓存，这里模型遵循协议。
• 基于,相对更加安全。

方案一：（常规写法：字段比较多的话，一个一个编解码比较麻烦）

Person.h文件

@interface Person : NSObject   //解归档需要遵循NSSecureCoding协议，并实现相关方法

@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSInteger sex;
@property (nonatomic, assign) NSInteger age;

@end

Person.m文件

@implementation Person

- (void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeInteger:self.sex forKey:@"sex"];
    [aCoder encodeInteger:self.age forKey:@"age"];
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super init]) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.sex = [aDecoder decodeIntegerForKey:@"sex"];
        self.age = [aDecoder decodeIntegerForKey:@"age"];
    }
    return self;
}

+ (BOOL)supportsSecureCoding {
    return YES;
}

@end

方案二：（利用YYModel处理编解码）

Person.h文件

@interface Person : NSObject   //解归档需要遵循NSSecureCoding协议，并实现相关方法

@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSInteger sex;
@property (nonatomic, assign) NSInteger age;

@end

Person.m文件

@implementation Person

- (void)encodeWithCoder:(NSCoder *)aCoder {
    [self yy_modelEncodeWithCoder:aCoder];
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    return [self yy_modelInitWithCoder:aDecoder];
}

+ (BOOL)supportsSecureCoding {
    return YES;
}

@end

方案三：（利用runtime处理编解码，要导入头文件#import ）

Person.h文件

@interface Person : NSObject   //解归档需要遵循NSSecureCoding协议，并实现相关方法

@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSInteger sex;
@property (nonatomic, assign) NSInteger age;

@end

Person.m文件

@implementation Person

- (void)encodeWithCoder:(NSCoder *)aCoder {
    unsigned int count = 0;
    // 获取所有实例变量
    Ivar *ivars = class_copyIvarList([self class], &count);
   // 遍历所有实例变量
    for (int i = 0; i < count; i++) {
        Ivar ivar = ivars[I];
        // 获取实例变量名
        const char *name = ivar_getName(ivar);
        NSString *key = [NSString stringWithUTF8String:name];
        // 通过KVC获取value值
        id value = [self valueForKey:key];
        // 编码
        [coder encodeObject:value forKey:key];
    }
    free(ivars); // C不会自动释放，需要手动释放。
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super init]) {
        unsigned int count = 0;
        // 获取所有实例变量
        Ivar *ivars = class_copyIvarList([self class], &count);
        // 遍历所有实例变量
        for (int i = 0; i < count; i++) {
            Ivar ivar = ivars[i];
            // 获取实例变量名
            const char *name = ivar_getName(ivar);
            NSString *key = [NSString stringWithUTF8String:name];
            // 解码
            id value = [coder decodeObjectOfClass:[self class] forKey:key];
            // 通过KVC 设置value
            [self setValue:value forKey:key];
        }
        free(ivars); // C不会自动释放，需要手动释放。
    }
    return self;
}

+ (BOOL)supportsSecureCoding {
    return YES;
}

@end

ViewController.m文件

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    Person *person1 = [Person new];
    person1.name = @"程序猿";
    person1.sex = 1;
    person1.age = 26;
    
    Person *person2 = [Person new];
    person2.name = @"程序媛";
    person2.sex = 0;
    person2.age = 27;
    
    NSMutableArray *personArr = [NSMutableArray arrayWithCapacity:0];
    [personArr addObject:person1];
    [personArr addObject:person2];
    
    // 这里以缓存模型数组为例，缓存单个模型对象，直接把对应模型数组参数改为模型对象即可（存取都要更改）
    [self wirteToFile: personArr]; // 归档
    [self readFromFile]; // 解档
}

// 归档
- (void)wirteToFile:(NSArray *)dataArray {
    NSString *fileName = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject stringByAppendingPathComponent:@"archive.person"];
    if (@available(iOS 11.0, *)) {
        NSData *arrayData = [NSKeyedArchiver archivedDataWithRootObject:dataArray requiringSecureCoding:YES error:nil];
        [arrayData writeToFile:fileName atomically:YES];
    } else {
        NSData *arrayData = [NSKeyedArchiver archivedDataWithRootObject:dataArray];
        [arrayData writeToFile:fileName atomically:YES];
    }
}

// 解档
- (void)readFromFile {
    NSString *fileName = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject stringByAppendingPathComponent:@"archive.person"];
    NSData *resultData = [[NSData alloc]initWithContentsOfFile:fileName];
    //  解档模型数组使用unarchivedArrayOfObjectsOfClass: fromData: error: 此方法iOS 14.0可用
    // 解档单个模型数据可以使用 unarchivedObjectOfClass: fromData: error:，iOS 11.0可用
    if (@available(iOS 14.0, *)) {
        NSArray *resultArray = [NSKeyedUnarchiver unarchivedArrayOfObjectsOfClass:[Person class] fromData:resultData error:nil];
        NSLog(@"%@",resultArray);
    } else {
        NSArray *resultArray = [NSKeyedUnarchiver unarchiveObjectWithData:resultData];
        NSLog(@"%@",resultArray);
    }
}

@end