NSCopying和NSCoding对象序列化反序列化基础详解你要知道的NSCopying、NSCoding协议及对象序列化和反序列化都在这里

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        NSString *string = @"Jiaming Chen";
        NSString *copyString = [string copy];
        NSMutableString *mutableCopyString = [string mutableCopy];
        //输出: 0x1000020a8 0x1000020a8 0x10058ccb0
        NSLog(@"%p %p %p", string, copyString, mutableCopyString);
        
        NSMutableString *mutableString = [[NSMutableString alloc] initWithString:@"Jiaming Chen"];
        NSString *copyMutableString = [mutableString copy];
        NSMutableString *mutableCopyMutableString = [mutableString mutableCopy];
        //输出: 0x100403f90 0x100403ef0 0x100403fd0
        NSLog(@"%p %p %p", mutableString, copyMutableString, mutableCopyMutableString);
        
        NSString *str = [[NSMutableString alloc] initWithString:@"Jiaming Chen"];
        NSString *copyStr = [str copy];
        NSMutableString *mutableCopyStr = [str mutableCopy];
        //输出: 0x100404060 0x7fffa86ddd40 0x1004040a0
        NSLog(@"%p %p %p", str, copyStr, mutableCopyStr);
        
        NSString *errorStr = @"Jiaming Chen";
        NSMutableString *errorMutableStr = errorStr;
        NSString *copyErrorMutableStr = [errorMutableStr copy];
        NSMutableString *mutableCopyErrorMutableStr = [errorMutableStr mutableCopy];
        //输出: 0x100002060 0x100002060 0x100002060 0x10440fbb0
        NSLog(@"%p %p %p %p", errorStr, errorMutableStr, copyErrorMutableStr, mutableCopyErrorMutableStr);
    }
}

@interface Account: NSObject <NSCopying>

@property (nonatomic, strong) NSMutableString *accountNumber;
@property (nonatomic, assign) double balance;

@end

@implementation Account

@synthesize accountNumber = _accountNumber;
@synthesize balance = _balance;

- (instancetype)copyWithZone:(NSZone *)zone
{
    //调用NSObject的类方法allocWithZone创建一个新的对象
    Account *account = [[self class] allocWithZone:zone];
    //使用mutableCopy获取一个可变的副本对象实现深拷贝
    //如果不调用mutableCopy而直接赋值，则是浅拷贝，另一个对象的修改会影响到当前对象的值
    account.accountNumber = [self.accountNumber mutableCopy];
    account.balance = self.balance;
    return account;
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        NSMutableString *mutableStr = [[NSMutableString alloc] initWithString:@"Jiaming Chen"];
        
        Account *account = [[Account alloc] init];
        account.accountNumber = mutableStr;
        account.balance = 666.66;
        
        Account *accountBak = [account copy];
        
        //输出:0x100407460 0x100407580
        NSLog(@"%p %p", account, accountBak);
        //输出:0x1004074d0 0x100407600 0x100407be0
        NSLog(@"%p %p %p", account.accountNumber, accountBak.accountNumber, mutableStr);

    }
    return 0;
}

/*将对象编码
序列化对象时调用该方法，在该方法中序列化对象的每一个属性
一般使用encodeObject:forKey:方法序列化属性
*/
- (void)encodeWithCoder:(NSCoder *)aCoder;

/*
将数据解码并创建一个对象
反序列化时调用该方法，在该方法中反序列化对象的每一个熟悉
一般使用decodeObject:forKey方法反序列化属性
*/
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder;

@interface Account: NSObject <NSCoding>

@property (nonatomic, copy) NSString *accountNumber;
@property (nonatomic, assign) double balance;

@end

@implementation Account

@synthesize accountNumber = _accountNumber;
@synthesize balance = _balance;

//反序列化
- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    /*NSObject没有遵守NSCoding协议，因此调用父类的init构造方法
      如果继承的父类遵守NSCoding协议需要调用父类的initWithCoder:方法
      [super initWithCoder:aDecoder]
    */
    if (self = [super init])
    {
        self.accountNumber = [aDecoder decodeObjectForKey:@"kaccountNumber"];
        self.balance = [aDecoder decodeDoubleForKey:@"kbalance"];
    }
    return self;
}

//序列化
- (void)encodeWithCoder:(NSCoder *)aCoder
{
    //序列化与序列化的顺序不需要保持一致，因为使用了key来检索，可以乱序
    [aCoder encodeObject:self.accountNumber forKey:@"kaccountNumber"];
    [aCoder encodeDouble:self.balance forKey:@"kbalance"];
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        Account *account = [[Account alloc] init];
        account.accountNumber = @"1603121434";
        account.balance = 666.66;
        //输出: <Account: 0x10040c2f0> 1603121434 666.660000
        NSLog(@"%@ %@ %lf", account, account.accountNumber, account.balance);
        //将对象持久化到本地文件
        [NSKeyedArchiver archiveRootObject:account toFile:@"account.archiver"];
        //从本地文件中将数据反序列化创建对象
        Account *a = [NSKeyedUnarchiver unarchiveObjectWithFile:@"account.archiver"];
        //输出: <Account: 0x100506860> 1603121434 666.660000
        NSLog(@"%@ %@ %lf", a, a.accountNumber, a.balance);

    }
    return 0;
}