归档,在其他语言中又叫“序列化”,就是将对象保存到硬盘;解档,在其他语言又叫“反序列化”就是将硬盘文件还原成对象。其实归档就是数据存储的过程,在IOS中数据的存储有五种方式:
- xml属性列表(plist归档)
- NSUserDefaults(偏好设置)
- NSKeyedArchiver归档(加密形式)
- SQLite3(嵌入式数据库)
- Core Data(面向对象方式的嵌入式数据库)
当然关于2、4、5点不是我们今天介绍的重点,这个在IOS开发过程中我们会重点说到。
xml属性列表
首先我们先来看一下xml属性列表,xml属性列表进行归档的方式是将对象存储在一个plist文件中,这个操作起来比较简单,其实相当于xml序列化。但是同时它也有缺点:一是这种方式是明文保存的;二是这种方式操作的对象有限,只有NSArray、NSMutableArray、NSDictionary、NSMutableDictionary支持(归档时只要调用对应的writeToFile方法即可,解档调用arrayWithContentsOfFile或dictionaryWithContentsOfFile,注意像NSString、NSNumber、NSData即使有这个方法它存储的也不是xml格式)。
//
// main.m
// FoundationFramework
//
// Created by Kenshin Cui on 14-2-16.
// Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//
#import <Foundation/Foundation.h>
//xml属性
void test1(){
//数组
NSString *path=@"/Users/kenshincui/Desktop/arrayXml.plist";
NSArray *array1=@[@"Kenshin",@"Kaoru",@"Rosa"];
[array1 writeToFile:path atomically:YES];
NSArray *array2=[NSArray arrayWithContentsOfFile:path];
[array2 enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"array2[%lu]=%@",idx,obj);
}];
/*结果:
array1[0]=Kenshin
array1[1]=Kaoru
array1[2]=Rosa
*/
//字典
NSString *path2=@"/Users/kenshincui/Desktop/dicXml.plist";
NSDictionary *dic1=@{@"name":@"Kenshin",@"age":@28,@"height":@172.5};
[dic1 writeToFile:path2 atomically:YES];
NSDictionary *dic2=[NSDictionary dictionaryWithContentsOfFile:path2];
[dic2 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
NSLog(@"dic2[%@]=%@",key,obj);
}];
/*结果:
dic2[height]=172.5
dic2[age]=28
dic2[name]=Kenshin
*/
}
int main(int argc,char *argv[]){
test1();
return 0;
}
生成的文件如下
NSKeyedArchiver归档
如果要针对更多对象归档或者需要归档时能够加密的话就需要使用NSKeyedArchiver进行归档和解档,使用这种方式归档的范围更广而且归档内容是密文存储。从归档范围来讲NSKeyedArchiver适合所有ObjC对象,但是对于自定义对象我们需要实现NSCoding协议;从归档方式来讲NSKeyedArchiver分为简单归档和复杂对象归档,简单归档就是针对单个对象可以直接将对象作为根对象(不用设置key),复杂对象就是针对多个对象,存储时不同对象需要设置不同的Key。
首先看一下系统对象两种归档方式(简单归档和复杂归档)
//
// main.m
// FoundationFramework
//
// Created by Kenshin Cui on 14-2-16.
// Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//
#import <Foundation/Foundation.h>
//系统对象简单归档
void test1(){
//NSString归档
NSString *str1=@"Hello,world!";
NSString *path1=@"/Users/kenshincui/Desktop/archiver1.arc";
if(![NSArchiver archiveRootObject:str1 toFile:path1]){
NSLog(@"archiver failed!");
}
//NSString解档
NSString *str2= [NSUnarchiver unarchiveObjectWithFile:path1];
NSLog(@"str2=%@",str2);//结果:str2=Hello,world!
//NSArray归档
NSString *path2=@"/Users/kenshincui/Desktop/archiver2.arc";
NSArray *array1=@[@"Kenshin",@"Kaoru",@"Rosa"];
if(![NSArchiver archiveRootObject:array1 toFile:path2]){
NSLog(@"archiver failed!");
}
//NSArray解档
NSArray *array2=[NSUnarchiver unarchiveObjectWithFile:path2];
[array2 enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"array2[%lu]=%@",idx,obj);
}];
/*结果:
array2[0]=Kenshin
array2[1]=Kaoru
array2[2]=Rosa
*/
}
//系统复杂对象归档(多对象归档)
void test2(){
/*归档*/
NSString *path1=@"/Users/kenshincui/Desktop/archiver3.arc";
int int1=89;
CGSize size1={12.5,16.8};
NSNumber *number1=@60.5;
NSString *str1=@"Hello,world!";
NSArray *array1=@[@"Kenshin",@"Kaoru",@"Rosa"];
NSDictionary *dic1=@{@"name":@"Kenshin",@"age":@28,@"height":@172.5};
//同时对多个对象进行归档
NSMutableData *data1=[[NSMutableData alloc]init];//定义一个NSMutableData用于临时存放数据
NSKeyedArchiver *archiver=[[NSKeyedArchiver alloc]initForWritingWithMutableData:data1];//定义归档对象
[archiver encodeInt:int1 forKey:@"int"];//对int1归档并指定一个key以便以后读取
[archiver encodeSize:size1 forKey:@"size"];
[archiver encodeObject:number1 forKey:@"number"];
[archiver encodeObject:str1 forKey:@"string"];
[archiver encodeObject:array1 forKey:@"array"];
[archiver encodeObject:dic1 forKey:@"dic"];
[archiver finishEncoding];//结束归档
[data1 writeToFile:path1 atomically:YES];//写入文件
/*解档*/
int int2;
CGSize size2;
NSNumber *number2;
NSString *str2;
NSArray *array2;
NSDictionary *dic2;
NSData *data2=[[NSData alloc]initWithContentsOfFile:path1];//读出数据到NSData
NSKeyedUnarchiver *unarchiver=[[NSKeyedUnarchiver alloc]initForReadingWithData:data2];
int2= [unarchiver decodeInt64ForKey:@"int"];
size2=[unarchiver decodeSizeForKey:@"size"];
number2=[unarchiver decodeObjectForKey:@"number"];
str2=[unarchiver decodeObjectForKey:@"string"];
array2=[unarchiver decodeObjectForKey:@"array"];
dic2=[unarchiver decodeObjectForKey:@"dic"];
[unarchiver finishDecoding];
NSLog(@"int2=%i,size=%@,number2=%@,str2=%@,array2=%@,dic2=%@",int2,NSStringFromSize(size2),number2,str2,array2,dic2);
/*结果:
int2=89,
size={12.5, 16.800000000000001},
number2=60.5,
str2=Hello,world!,
array2=(
Kenshin,
Kaoru,
Rosa
),
dic2={
age = 28;
height = "172.5";
name = Kenshin;
}
*/
}
int main(int argc,char *argv[]){
test1();
test2();
return 0;
}
接下来看一下自定义的对象如何归档,上面说了如果要对自定义对象进行归档那么这个对象必须实现NSCoding协议,在这个协议中有两个方法都必须实现:
-(void)encodeWithCoder:(NSCoder *)aCoder;通过给定的Archiver对消息接收者进行编码;
-(id)initWithCoder:(NSCoder *)aDecoder;从一个给定的Unarchiver的数据返回一个初始化对象;
这两个方法分别在归档和解档时调用。下面通过一个例子进行演示(注意对于自定义类的多对象归档与系统类多对象归档完全一样,代码中不再演示):
Person.h
//
// Person.h
// FoundationFramework
//
// Created by Kenshin Cui on 14-2-16.
// Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//
#import <Foundation/Foundation.h>
@interface Person : NSObject<NSCoding>
@property (nonatomic,copy) NSString *name;
@property (nonatomic,assign) int age;
@property (nonatomic,assign) float height;
@property (nonatomic,assign) NSDate *birthday;
@end
Person.m
//
// Person.m
// FoundationFramework
//
// Created by Kenshin Cui on 14-2-16.
// Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//
#import "Person.h"
@implementation Person
#pragma mark 解码
-(id)initWithCoder:(NSCoder *)aDecoder{
NSLog(@"decode...");
if (self=[super init]) {
self.name=[aDecoder decodeObjectForKey:@"name"];
self.age=[aDecoder decodeInt64ForKey:@"age"];
self.height=[aDecoder decodeFloatForKey:@"heiht"];
self.birthday=[aDecoder decodeObjectForKey:@"birthday"];
}
return self;
}
#pragma mark 编码
-(void)encodeWithCoder:(NSCoder *)aCoder{
NSLog(@"encode...");
[aCoder encodeObject:_name forKey:@"name"];
[aCoder encodeInt64:_age forKey:@"age" ];
[aCoder encodeFloat:_height forKey:@"height"];
[aCoder encodeObject:_birthday forKey:@"birthday"];
}
#pragma mark 重写描述
-(NSString *)description{
NSDateFormatter *formater1=[[NSDateFormatter alloc]init];
formater1.dateFormat=@"yyyy-MM-dd";
return [NSString stringWithFormat:@"name=%@,age=%i,height=%.2f,birthday=%@",_name,_age,_height,[formater1 stringFromDate:_birthday]];
}
@end
main.m
//
// main.m
// FoundationFramework
//
// Created by Kenshin Cui on 14-2-16.
// Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "Person.h"
int main(int argc,char *argv[]){
//归档
Person *person1=[[Person alloc]init];
person1.name=@"Kenshin";
person1.age=28;
person1.height=1.72;
NSDateFormatter *formater1=[[NSDateFormatter alloc]init];
formater1.dateFormat=@"yyyy-MM-dd";
person1.birthday=[formater1 dateFromString:@"1986-08-08"];
NSString *path1=@"/Users/kenshincui/Desktop/person1.arc";
[NSKeyedArchiver archiveRootObject:person1 toFile:path1];
//解档
Person *person2= [NSKeyedUnarchiver unarchiveObjectWithFile:path1];
NSLog(@"%@",person2);
/*结果:
name=Kenshin,age=28,height=0.00,birthday=1986-08-08
*/
return 0;
}