iOS 归档

写入数据

//1.文件路径    
    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"info.plist"];       
//1. 有个对象
    Student *student = [[Student alloc]init];
    student.name = @"11";    
    student.age = 10;          
//2.存储  归档    
    [NSKeyedArchiver archiveRootObject:student toFile:path];

读取数据

  NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"info.plist"];       
//反归档 ,解档
    Student *p = [NSKeyedUnarchiver unarchiveObjectWithFile:path];

注意:
如果使用归档

1. 该对象必须遵守NSCoding 协议 编码协议
2. 实现 encodeWithCoder方法
3. 实现:initWIthCoder方法

实现<NSCoding>协议方法

- (void)encodeWithCoder:(NSCoder *)coder{
   [coder encodeObject:self.name forKey:@"name"];
   [coder encodeInteger:self.age forKey:@"age"];
   
}
//反归档只是个过程, 告诉系统你读取的时候,想让别人读取哪些属性
- (instancetype)initWithCoder:(NSCoder *)decoder{
    if (self = [super init]) {
        self.name = [decoder decodeObjectForKey:@"name"];
        self.age  = [decoder decodeIntegerForKey:@"age"];
     }
     return self;
}