可以使用NSKeyedArchiver把數(shù)據(jù)保存到本地，在需要使用數(shù)據(jù)的時(shí)候使用NSKeyedUnarchiver來讀取數(shù)據(jù)，簡單的數(shù)據(jù)如下

- (void)saveAndReadSimpleData
{
    NSArray *array = @[@"1", @"2", @"3"];
    [NSKeyedArchiver archiveRootObject:array toFile:[self filePath]];
    NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile:[self filePath]];
}

- (NSString *)filePath
{
    NSString *documentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    return [documentPath stringByAppendingPathComponent:@"array.data"];
}```

但是大多數(shù)時(shí)候需要保存的數(shù)據(jù)都是自定義類的實(shí)例，例如我們有一個`Person`類，擁有`name`和`age`兩個屬性

@interface Person : NSObject
@property(nonatomic, copy) NSString *name;
@property(nonatomic, assign) NSInteger age;
@end

在使用上同上

• (void)saveAndReadCustomData
  {
  Person *p = [Person new];
  p.name = @"JC";
  p.age = 88;

  [NSKeyedArchiver archiveRootObject:p toFile:[self filePath]];
  Person *person = [NSKeyedUnarchiver unarchiveObjectWithFile:[self filePath]];
  }

編譯運(yùn)行的時(shí)候程序會奔潰并伴隨如下的錯誤 
`*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Person encodeWithCoder:]: unrecognized selector sent to instance 0x7fe1c872ec20'`

這是因?yàn)槭褂米远x的類進(jìn)行歸檔和解檔的時(shí)候需要實(shí)現(xiàn)協(xié)議`NSCoding`
在`Person.m`文件中實(shí)現(xiàn)`NSCoding`協(xié)議的兩個方法

• (instancetype)initWithCoder:(NSCoder *)coder
  {
  // self = [super initWithCoder:coder];
  //這里需要特別注意，調(diào)用的是super的init方法而不是initWithCoder:coder方法
  self = [super init];
  if (self) {
  self.name = [coder decodeObjectForKey:@"name"];
  self.age = [coder decodeIntegerForKey:@"age"];
  }
  return self;
  }

• (void)encodeWithCoder:(NSCoder *)aCoder
  {
  [aCoder encodeObject:self.name forKey:@"name"];
  [aCoder encodeInteger:self.age forKey:@"age"];
  }

再次運(yùn)行程序，錯誤消失，能正常地進(jìn)行歸檔和解檔
######這里需要特別注意的是在`- (instancetype)initWithCoder:(NSCoder *)coder`方法中，調(diào)用的是`self = [super init];`，而不是`self = [super initWithCoder:coder];`，調(diào)用后面的方法會報(bào)父類沒有相應(yīng)方法的錯誤#####