第二十三讲：文件归档与协议

Sian

1、对象进行归档操作时需要用到协议NSCoding，前面已经有讲到存档与解档操作，这里引进协议的概念，在协议中实现归档
2、创建一个类Person
3、在Person中使用协议NSCoding来实现存档操作
4、在implemetation中实现协议NSCoding的两个方法（必须实现）
5、对象person1归档到data中，data1将解档data；
6、创建person对象，将data1解档的数据赋值给person

Person.h

1. //
2. //  Person.h
3. //  NSCoding
4. //
5. //  Created by yusian on 14-1-21.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
11. @interface Person : NSObject <NSCoding>
13. @property (retain) NSString * name;
14. @property int age;
15. @property (retain) Person * child;
17. @end

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Person.m

1. //
2. //  Person.m
3. //  NSCoding
4. //
5. //  Created by yusian on 14-1-21.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import "Person.h"
11. @implementation Person
13. - (void)encodeWithCoder:(NSCoder *)aCoder {
14.     [aCoder encodeObject:_name forKey:@"name"];
15.     [aCoder encodeInt:_age forKey:@"age"];
16.     [aCoder encodeObject:_child forKey:@"chile"];
17. }
18. - (id)initWithCoder:(NSCoder *)aDecoder {
19.     if (self = [super init]) {
20.         self.age = [aDecoder decodeIntForKey:@"age"];
21.         self.name = [aDecoder decodeObjectForKey:@"name"];
22.         self.child = [aDecoder decodeObjectForKey:@"chile"];
23.     }
24.     return self;
25. }
26. @end

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main.m

1. //
2. //  main.m
3. //  NSCoding
4. //
5. //  Created by yusian on 14-1-21.
6. //  Copyright (c) 2014年 yusian. All rights reserved.
7. //
9. #import <Foundation/Foundation.h>
10. #import "Person.h"
12. int main(int argc, const char * argv[])
13. {
15.     @autoreleasepool {
16.         
17.         Person * person1 = [[Person alloc] init];
18.         Person * person2 = [[Person alloc] init];
19.         
20.         person1.age = 30;
21.         person1.name = @"deny";
22.         person1.child = person2;
23.         
24.         NSData * data = [NSKeyedArchiver archivedDataWithRootObject:person1];
25.         [data writeToFile:@"/tmp/file.plist" atomically:YES];
26.         
27.         NSData * data1 = [NSData dataWithContentsOfFile:@"/tmp/file.plist"];
28.         Person * person = [NSKeyedUnarchiver unarchiveObjectWithData:data1];
29.         
30.         NSLog(@"Person %@ age is %d",person.name, person.age);
31.         
32.     }
33.     return 0;
34. }

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输出结果：

1. 2014-01-21 22:46:20.541 NSCoding[2287:303] Person deny age is 30
2. Program ended with exit code: 0

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