转载自： http://www.cnblogs.com/yjmyzz/archive/2011/03/03/1969859.html
obj-c中有一类对象：NSArray,NSDictionary,NSString,NSNumber,NSDate,NSData以及它们的可变版本(指NSMutableArray,NSMutableDictionary...这一类) ，都可以方便的将自身的数据以某种格式(比如xml格式)序列化后保存成本地文件。
示例代码：NSArrayTest.h
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#import <Foundation/Foundation.h>
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#define FILE_NAME @"/tmp/data.txt"
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@interface
NSArrayTest
:
NSObject
{
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}
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|
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-(
void
) Test;
|
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@end
|
NSArrayTest.m
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#import "NSArrayTest.h"
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@implementation
NSArrayTest
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-(
void
) Test
|
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{
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NSArray
*arr = [
NSArray
arrayWithObjects:@
"one"
,@
"two"
,@
"three"
,
nil
];
//注:最后一个要以nil结尾
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[arr writeToFile:FILE_NAME atomically:
YES
];
//(序列化为xml格式后)保存文件
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|
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NSArray
*arr2 = [
NSArray
arrayWithContentsOfFile:FILE_NAME];
//read file
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NSLog
(@
"%@"
,arr2);
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|
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}
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|
@end
|
运行结果：
2011-03-03 14:20:01.501 pList[1246:a0f] (
one,
two,
three
)
one,
two,
three
)
如果查看/tmp/data.txt，能看到下面的内容：
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|
<?
xml
version
=
"1.0"
encoding
=
"UTF-8"
?>
|
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|
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "
http://www.apple.com/DTDs/PropertyList-1.0.dtd
">
|
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|
<
plist
version
=
"1.0"
>
|
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|
<
array
>
|
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|
<
string
>one</
string
>
|
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|
<
string
>two</
string
>
|
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|
<
string
>three</
string
>
|
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|
</
array
>
|
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|
</
plist
>
|
如果你用来存放数据的类是自己定义的，并不是上面这些预置的对象，那么就要借助
正式协议NSCoding
来实现序列化和反序列化。
比如，我们有一个自己的类Sample.h
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|
#import <Foundation/Foundation.h>
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|
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@interface
Sample :
NSObject
<
NSCoding
> {
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|
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|
NSString
* name;
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int
magicNumber;
|
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float
shoeSize;
|
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NSMutableArray
*subThingies;
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}
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@property
(
copy
)
NSString
* name;
|
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@property
int
magicNumber;
|
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@property
float
shoeSize;
|
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@property
(retain)
NSMutableArray
*subThingies;
|
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|
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|
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-(
id
) initWithName:(
NSString
*)n magicNumber:(
int
)m shoeSize:(
float
) ss;
|
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|
@end
|
这里我们定义几个不同类型的属性，有字符串，有整数，有浮点数，还有一个可变长的数组对象
Sample.m
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#import "Sample.h"
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@implementation
Sample
|
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|
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@synthesize
name;
|
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@synthesize
magicNumber;
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@synthesize
shoeSize;
|
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@synthesize
subThingies;
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|
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-(
id
) initWithName:(
NSString
*)n magicNumber:(
int
)m shoeSize:(
float
)ss
|
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{
|
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if
(
self
=[
super
init])
|
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{
|
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self
.name = n;
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self
.magicNumber = m;
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self
.shoeSize = ss;
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self
.subThingies = [
NSMutableArray
array];
|
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}
|
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return
(
self
);
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}
|
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|
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-(
void
) dealloc
|
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|
{
|
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|
[name release];
|
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|
[subThingies release];
|
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|
[
super
dealloc];
|
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|
}
|
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|
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//将对象编码(即:序列化)
|
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|
-(
void
) encodeWithCoder:(
NSCoder
*)aCoder
|
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|
{
|
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|
[aCoder encodeObject:name forKey:@
"name"
];
|
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|
[aCoder encodeInt:magicNumber forKey:@
"magicNumber"
];
|
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|
[aCoder encodeFloat:shoeSize forKey:@
"shoeSize"
];
|
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|
[aCoder encodeObject:subThingies forKey:@
"subThingies"
];
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}
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|
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|
//将对象解码(反序列化)
|
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|
-(
id
) initWithCoder:(
NSCoder
*)aDecoder
|
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|
{
|
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|
if
(
self
=[
super
init])
|
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|
{
|
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|
self
.name = [aDecoder decodeObjectForKey:@
"name"
];
|
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|
self
.magicNumber = [aDecoder decodeIntForKey:@
"magicNumber"
];
|
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|
self
.shoeSize = [aDecoder decodeFloatForKey:@
"shoeSize"
];
|
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|
self
.subThingies = [aDecoder decodeObjectForKey:@
"subThingies"
];
|
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}
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return
(
self
);
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}
|
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|
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-(
NSString
*) description
|
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{
|
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|
NSString
*description = [
NSString
stringWithFormat:@
"%@:%d/%.1f %@"
,name,magicNumber,shoeSize,subThingies];
|
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|
return
(description);
|
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|
}
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|
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|
@end
|
注意其中的：
encodeWithCoder
与
initWithCoder
，这是NSCoding协议中定义的二个方法，用来实现对象的编码与解码。其实现也不复杂，利用的是key-value的经典哈希结构。当然一般在编码中，对于key的名字字符串，建议用define以常量方式事先定义好，以避免开发人员字符串键入错误。
测试一下：
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#import <Foundation/Foundation.h>
|
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|
#import "Sample.h"
|
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|
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|
int
main (
int
argc,
const
char
* argv[]) {
|
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|
NSAutoreleasePool
* pool = [[
NSAutoreleasePool
alloc] init];
|
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|
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|
Sample *s1 = [[Sample alloc] initWithName:@
"thing1"
magicNumber:42 shoeSize:10.5];
|
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|
[s1.subThingies addObject:@
"1"
];
|
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|
[s1.subThingies addObject:@
"2"
];
|
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|
NSLog
(@
"%@"
,s1);
|
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|
NSData
*data1 = [
NSKeyedArchiver
archivedDataWithRootObject:s1];
//将s1序列化后,保存到NSData中
|
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|
[s1 release];
|
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|
[data1 writeToFile:@
"/tmp/data.txt"
atomically:
YES
];
//持久化保存成物理文件
|
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|
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|
NSData
*data2 = [
NSData
dataWithContentsOfFile:@
"/tmp/data.txt"
];
//读取文件
|
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|
Sample *s2 = [
NSKeyedUnarchiver
unarchiveObjectWithData:data2];
//反序列化
|
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|
NSLog
(@
"%@"
,s2);
|
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|
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|
[pool drain];
|
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|
return
0;
|
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|
}
|
运行结果：
2011-03-03 14:36:48.540 pList[1322:a0f] thing1:42/10.5 (
1,
2
)
2011-03-03 14:36:48.548 pList[1322:a0f] thing1:42/10.5 (
1,
2
)
查看/tmp/data.txt，能看到以下内容：
由于经过了编码，里面的内容没有象前面的NSArray那样可读性强。
作者：
菩提树下的杨过
出处： http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
出处： http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
