iOS11以上系统归档存储数据

iOS11以上归档api废弃了老方法，archiveRootObject:toFile: 但是到iOS12还可以用，所以可以用下面新方法代替

• 存储字符串类型

    NSError  *error = nil;
    NSString *docsDir;
    NSArray  *dirPaths;
    // 获取存储路径
    dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    docsDir = [dirPaths firstObject];
    NSString *databasePath = [docsDir stringByAppendingPathComponent:@"appData.data"];
    
    // iOS12 归档实现代码
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:@"iOS" requiringSecureCoding:NO error:&error];
    [data writeToFile:databasePath options:NSDataWritingAtomic error:&error];
    NSLog(@"Write returned error: %@", [error localizedDescription]);
    
    // iOS12 解档实现代码
    NSData *newData = [NSData dataWithContentsOfFile:databasePath];
    NSString *fooString = [NSKeyedUnarchiver unarchivedObjectOfClass:[NSString class] fromData:newData error:&error];
    NSLog(@"%@",fooString);

• 存储自定义对象归档解档
  创建Person类继承自NSObject ，遵守NSCoding或者NSSecureCoding协议，重写两个方法。"supportsSecureCoding"是NSSecureCoding协议下的重要属性，如果采用NSSecureCoding协议，必须重写supportsSecureCoding 方法并返回YES

#import "Person.h"

#pragma mark - 实现NSSecureCoding协议
@interface Person () <NSSecureCoding>

@end
@implementation Person
#pragma mark - 归档实现
- (void)encodeWithCoder:(NSCoder *)coder
{
    [coder encodeObject:self.name forKey:@"name"];
    [coder encodeInt:self.age forKey:@"age"];
}
#pragma mark - 解档实现
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    if (self) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.age = [aDecoder decodeIntForKey:@"age"];
    }
    return self;
}
#pragma mark - 这个必须实现 , 否则解档文件的时候会返回null
+ (BOOL)supportsSecureCoding {
    return YES;
}

@end

• 归档

    NSError  *error = nil;
    Person *person = [[Person alloc] init];
    person.name = @"小明";
    person.age = 10;
    // 获取存储路径
    NSString *dirPaths = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *dataPath = [dirPaths stringByAppendingPathComponent:@"appData.data"];
    
    // 归档实现代码
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:person requiringSecureCoding:NO error:&error];
    [data writeToFile:dataPath options:NSDataWritingAtomic error:&error];
    NSLog(@"Write returned error: %@", [error localizedDescription]);

• 解档

    NSError *error;
    NSString *dirPaths = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *databasePath = [dirPaths stringByAppendingPathComponent:@"appData.data"];
    NSData *newData = [NSData dataWithContentsOfFile:databasePath];
    Person *person = [NSKeyedUnarchiver unarchivedObjectOfClass:Person.class fromData:newData error:&error];
    NSLog(@"name=%@,age=%d",person.name,person.age);