一、归档介绍
1.归档是将数据持久化的一种方式，一般针对于比较复杂对象，比如自定义的对象，来进行数据持久化操作。
2.归档的对象需要遵循NSCoding协议，存储的时候调用encodeWithCoder：方法，读取的时候调用initWithCoder：方法。
3.将数据写入本地需要调用 [NSKeyedArchiver archiveRootObject:per toFile:filePath]，filePath为存储的路径。
4.从本地读取数据需要调用[NSKeyedUnarchiver unarchiveObjectWithFile:filePath]，filePath为存储的路径。
二、对自定义对象进行归档
1.自定义Person类服从NSCoding协议
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface Person : NSObject <NSCoding>
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) int age;
@property (nonatomic, assign) CGFloat height;
@end
2.实现协议方法encodeWithCoder：和initWithCoder：
#import "Person.h"
@implementation Person
//写入文件时调用 -- 将需要存储的属性写在里面
- (void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:self.name forKey:@"name"];
[aCoder encodeInt:self.age forKey:@"age"];
[aCoder encodeFloat:self.height forKey:@"height"];
}
//从文件中读取时调用 -- 将需要存储的属性写在里面
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder {
if (self = [super init]) {
self.name = [aDecoder decodeObjectForKey:@"name"];
self.age = [aDecoder decodeIntForKey:@"age"];
self.height = [aDecoder decodeFloatForKey:@"height"];
}
return self;
}
@end
3.写入与读取
写入：[NSKeyedArchiver archiveRootObject:per toFile:filePath]
读取： [NSKeyedUnarchiver unarchiveObjectWithFile:filePath]
#import "ViewController.h"
#import "Person.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self saveModel];
[self readModel];
}
//存储数据
- (void)saveModel {
Person *per = [Person new];
per.name = @"xiaoming";
per.age = 18;
per.height = 180;
NSString *filePath = [self getFilePath];
//将对象per写入
[NSKeyedArchiver archiveRootObject:per toFile:filePath];
}
//读取数据
- (void)readModel {
NSString *filePath = [self getFilePath];
//取出per对象
Person *per = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];
NSLog(@"%@ -- %@ -- %d -- %.0f", per, per.name, per.age, per.height);
}
//获得全路径
- (NSString *)getFilePath {
//获取Documents
NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
//在Documents下创建Person.data文件
NSString *filePath = [doc stringByAppendingPathComponent:@"Person.data"];
return filePath;
}
@end
readModel：方法中打印出存储的per对象相关信息，则对自定义对象Person数据持久化成功
