iOS：文件归档和解归档的详解和使用
文件归档和解归档：
+ (BOOL)archiveRootObject:(id)rootObject toFile:(NSString *)path;//归档
+ (id)unarchiveObjectWithFile:(NSString *)path;//接归档
2、NSKeyedArchiver 归档、解归档(自定义的对象,必须要实现<NSCoding>协议)
- (void)encodeWithCoder:(NSCoder *)aCoder;//归档的协议方法，序列化
- (id)initWithCoder:(NSCoder *)aDecoder;//解归档的协议方法，反序列化
+ (BOOL)archiveRootObject:(id)rootObject toFile:(NSString *)path;//归档
+ (id)unarchiveObjectWithFile:(NSString *)path;//接归档
3、对多个对象进行归档、解归档
- (instancetype)initForWritingWithMutableData:(NSMutableData *)data;//用一个可变的data创建归档对象
- (void)encodeObject:(id)objv forKey:(NSString *)key;//将对象归档
- (void)finishDecoding//完成归档(必须执行)
- (BOOL)writeToFile:(NSString *)path atomically:(BOOL)useAuxiliaryFile//将数据写进归档文件中
- (instancetype)initForReadingWithData:(NSData *)data;//用一个data创建解归档对象，这个data由文件中获取而来
- (id)decodeObjectForKey:(NSString *)key;//解归档
文件归档和解归档的使用：
一、对内置单个对象进行归档和解归档
1.获取归档文件的路径(归档文件名可以自己随意取名)
1 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 2 3 NSString *documentPath = [documents lastObject]; 4 5 NSString *archiveFileName = [documentPath stringByAppendingPathComponent:@"array.arc"];
2.准备归档的对象数据
1 NSArray *array = @[@1,@5,@3,@3,@4,@2];
3.对数据进行归档(根据flag标识进行判断，如果返回的是YES,归档成功；反之，归档失败)
1 if([NSKeyedArchiver archiveRootObject:array toFile:archiveFileName]) 2 3 { 4 5 NSLog(@"归档对象成功"); 6 7 }
4.对数据进行解归档
1 NSArray *array2 = [NSKeyedUnarchiver unarchiveObjectWithFile:archiveFileName];
二、对自定义的单个对象进行归档和解归档(由于自定义对象不具有归档的性质，所以要实现归档和解归档，首先必须实现<NSCoding>协议)
1.自定义一个归档对象类，实现协议
Person.h
1 #import <Foundation/Foundation.h> 2 @interface Person : NSObject<NSCoding> 3 @property (copy,nonatomic)NSString *name; 4 @property (assign,nonatomic)NSInteger age; 5 @property (assign,nonatomic)char gender; 6 -(id)initWithName:(NSString*)name andAge:(NSInteger)age andChar:(char)gender; 7 @end
Person.m
1 #import "Person.h" 2 @implementation Person 3 -(id)initWithName:(NSString*)name andAge:(NSInteger)age andChar:(char)gender 4 { 5 self = [super init]; 6 if(self) 7 { 8 _name = [name copy]; 9 _age = age; 10 _gender = gender; 11 } 12 return self; 13 } 14 -(NSString*)description 15 { 16 return [NSString stringWithFormat:@"name:%@,age:%ld,gender:%c",_name,_age,_gender]; 17 } 18 #pragma mark -<NSCoding> 19 //归档的协议方法 20 -(void)encodeWithCoder:(NSCoder *)aCoder//将归档对象序列化 21 { 22 [aCoder encodeObject:_name forKey:@"name"]; 23 [aCoder encodeInteger:_age forKey:@"age"]; 24 [aCoder encodeInt:_gender forKey:@"gender"]; 25 } 26 //解归档的协议方法 27 -(id)initWithCoder:(NSCoder *)aDecoder //将归档对象反序列化 28 { 29 self = [super init]; 30 if(self) 31 { 32 _name = [[aDecoder decodeObjectForKey:@"name"] copy]; 33 _age = [aDecoder decodeIntegerForKey:@"age"]; 34 _gender = [aDecoder decodeIntForKey:@"gender"]; 35 } 36 return self; 37 } 38 @end
2.获取归档文件的路径(归档文件名可以自己随意取名)
1 NSString *homePath = NSHomeDirectory(); 2 3 NSString *documentPath = [homePath stringByAppendingPathComponent:@"documents"]; 4 5 NSString *arcviFileName = [documentPath stringByAppendingPathComponent:@"person.arc"];
3.创建该类归档对象并将其初始化
1 Person *person = [[Person alloc]initWithName:@"Tom" andAge:23 andChar:'M'];
4.将归档对象归档
1 if([NSKeyedArchiver archiveRootObject:person toFile:arcviFileName]) 2 { 3 NSLog(@"归档成功"); 4 } 5 else 6 { 7 NSLog(@"归档失败"); 8 }
5.将归档的对象解归档
1 Person *person2 = [NSKeyedUnarchiver unarchiveObjectWithFile:arcviFileName];
三、对多个对象进行归档和解归档(前面的两种方式都是针对于单个对象进行归档和解归档，如果需要对多个对象进行归档，它们就无用武之地了，局限性很大，因此，这里介绍一个新的归档方式，多对象归档和解归档)
1.获取的文件路径(归档文件名可以自己随意取名)
1 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 2 NSString *documentPath = [documents lastObject]; 3 NSString *archiveFileName = [documentPath stringByAppendingPathComponent:@"objects.arc"];
2.准备要归档的多个归档对象数据
1 NSString *useName = @"admin"; 2 NSArray *scores = @[@90,@89,@90.5,@98]; 3 NSString *adress = @"北京市昌平区东三旗";
3.对归档对象进行归档
1 //归档多个对象(将多个对象读到data中) 2 //1.用一个可变的data对象创建归档对象 3 NSMutableData *data = [[NSMutableData alloc]init]; 4 NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data]; 5 6 //2.归档多个对象 7 [archiver encodeObject:useName forKey:@"userName"]; 8 [archiver encodeObject:scores forKey:@"scores"]; 9 [archiver encodeObject:adress forKey:@"adress"]; 10 11 //3.完成归档（必须要实现的方法,要不然归档失败） 12 [archiver finishEncoding]; 13 14 //4.将可变的data写进文件 15 [data writeToFile:archiveFileName atomically:YES];
说明：这种归档方式，其实就是先将所有的要归档的对象先存入到一个可变的NSMutableData对象data中，然后通过data创建的归档对象将data的数据归档到归档文件中就是了。
4.将归档对象进行解归档
1 //解归档多个对象 2 //1.从文件中读出一个data 3 NSData *data2 = [NSData dataWithContentsOfFile:archiveFileName]; 4 //2.由data创建解归档对象 5 NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:data2]; 6 7 //3.按照key解出多个对象 8 NSString *userName2 = [unarchiver decodeObjectForKey:@"userName"]; 9 NSArray *scores2 = [unarchiver decodeObjectForKey:@"scores"]; 10 NSString *adress2 = [unarchiver decodeObjectForKey:@"adress"]; 11 12 NSLog(@"uesrName:%@,scores:%@,adress:%@",userName2,scores2,adress2);
说明：这种解归档方式，其实就是从归档文件先读取data，然后通过data创建解归档对象根据指定的键将多个对象都解归档出来就是了。
演示如下：
2015-09-20 11:16:56.563 05-一个文件多个归档[908:42275] uesrName:admin,scores:( 90, 89, "90.5", 98 ),adress:北京市昌平区东三旗
