數據持久化

先上幾個圖片解釋一下什麼是沙盒

然後是簡單對象的數據持久化，複雜對象數據持久化，要繼承一個協議
NSCopying，重寫裏面的兩個方法。

- (void)encodeWithCoder:(NSCoder *)aCoder;
- (id)initWithCoder:(NSCoder *)aDecoder; // NS_DESIGNATED_INITIALIZER

下面直接上代碼

#import "ViewController.h"
#import "Person.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

#pragma mark -------------獲取沙盒下的文件目錄

    //1.獲取沙盒中Documents這個文件夾得路徑

    //第一種方式

    NSString *documentsPath =  NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES).lastObject;


    NSLog(@"%@",documentsPath);


    //第二種方式

     NSString *user =  NSHomeDirectory();

    NSString *documentPath1 = [user stringByAppendingPathComponent:@"Documents"];

    NSLog(@"%@",documentPath1);

    //獲取應用程序包
    NSLog(@"%@",[NSBundle mainBundle].resourcePath);

#pragma mark------------簡單對象持久化

    NSString *string = @"I love you so much";

    //1.存儲路徑

    NSString *filePath = [documentsPath stringByAppendingPathComponent:@"string.txt"];

    //2.將字符串寫入文件

    [string writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];


    //3.讀取文件中的字符串
    NSString *str = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];

    NSLog(@"%@",str);

    //4.將數組寫入未見

#warning mark ------------如果想把數組array直接寫入文件，數組中的文件必須是簡單對象（NSString，NSArray）

    //1.拼接存儲路徑

    NSString *arrPath = [documentsPath stringByAppendingPathComponent:@"array.txt"];
    NSArray *arr = @[@"a",@"b",@"c"];

    //2.寫入文件
    [arr writeToFile:arrPath atomically:YES];

    //3.從文件中讀取數組

    NSArray *array = [NSArray arrayWithContentsOfFile:arrPath];

    NSLog(@"%@",array);

//將字典持久化
    NSDictionary *dic = @{@"name":@"張三",@"age":@"19",@"sex":@"男"};

    NSString *dicPath = [documentsPath stringByAppendingPathComponent:@"dictionary.txt"];

    [dic writeToFile:dicPath atomically:YES];

    NSLog(@"%@",dicPath);

    NSDictionary *testDic = [NSDictionary dictionaryWithContentsOfFile:dicPath];

    for (NSString *key in testDic) {
        NSLog(@"%@",[testDic objectForKey:key]);
    }

    //將NSData數據持久化

    UIImage *image = [UIImage imageNamed:@"1.jpg"];

    NSData *data = UIImageJPEGRepresentation(image, 1.0);


    //存儲數據

    NSString *dataPath = [documentsPath stringByAppendingPathComponent:@"data.txt"];

    [data writeToFile:dataPath atomically:YES];


#pragma mark ----------NSFileManager(文件管理類）

    //獲取緩存文件夾所在路徑

    NSString *cachesPath = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;

    NSDictionary *dic1 = @{@"name":@"李四"};


    //在cachesPath路徑下創建一個文件夾

    NSString *directoryPath = [cachesPath stringByAppendingPathComponent:@"path"];


    //創建一個文件管理器對象
    NSFileManager *fielMager = [NSFileManager defaultManager];

    //根據路徑創建文件夾

    NSDictionary *fileData = @{@"createTime":@"2015-9-9"};

    [fielMager createDirectoryAtPath:directoryPath withIntermediateDirectories:YES attributes:fileData error:nil];

    //拼接存儲路徑,存到文件中，而不是存到文件夾中
    NSString *dicPath1 = [directoryPath stringByAppendingPathComponent:@"dic.jpg"];

    [dic1 writeToFile:dicPath1 atomically:YES];

    //創建文件,這個方法存儲的數據是NSData
    [fielMager createFileAtPath:dicPath1 contents:data attributes:fileData];


    //刪除指定的文件,先判斷給定的文件路徑是否真實存在
    if ([fielMager fileExistsAtPath:dicPath1]) {

        NSLog(@"%d",[fielMager fileExistsAtPath:dicPath1]);

        [fielMager removeItemAtPath:dicPath1 error:nil];
    }


#pragma mark -------------NSUserDefaults 也是單例類

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    [defaults setValue:@"yaxin" forKey:@"name"];

    [defaults setValue:@"123" forKey:@"password"];

    //立即同步到文件中
    [defaults synchronize];

    NSString *name = [defaults valueForKey:@"name"];

    NSString *pwd = [defaults valueForKey:@"password"];

    NSLog(@"%@,    %@",name,pwd);


#pragma mark ------------複雜對象持久化

    //過程：（複雜對象->歸檔->NSData->writeToFile)
    Person *person = [[Person alloc]init];
    person.name = @"張三";
    person.gender = @"男";
    person.age = 23;

    NSMutableData *mutData = [NSMutableData data];
    //創建歸檔器
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:mutData];

    //進行歸檔
    [archiver encodeObject:person forKey:@"person"];

    //結束歸檔
    [archiver finishEncoding];

    //將歸檔之後的NSData數據，寫入文件
    //①存儲路徑
    NSString *personPath = [cachesPath stringByAppendingPathComponent:@"person.txt"];
    //②寫入文件

    [mutData writeToFile:personPath atomically:YES];

    NSLog(@"%@",mutData);

#pragma mark --------------反歸檔（讀取複雜對象）

    //過程：（讀取文件->NSData - >反歸檔-》複雜對象那個）
    //從文件中讀取NSData數據

    NSData *personData = [NSData dataWithContentsOfFile:personPath];

    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:personData];

    //使用反歸檔工具對resultData數據進行反歸檔

    Person *person1 = [unarchiver decodeObjectForKey:@"person"];

    //結束反歸檔
    [unarchiver finishDecoding];

    NSLog(@"%@,%@,%lu",person1.name,person1.gender,person1.age);

    // Do any additional setup after loading the view, typically from a nib.
}

對於複雜對象

#import <Foundation/Foundation.h>

//複雜對象歸檔第一步：遵守NSCoding協議
@class Dog;
@interface Person : NSObject<NSCopying>



@property(nonatomic,retain)NSString * name;
@property(nonatomic,retain)NSString * gender;
@property(nonatomic,assign)NSInteger age;

@property(nonatomic,retain)Dog * dog;

@end


#import "Person.h"

@implementation Person


#pragma mark ===========進行編碼
- (void)encodeWithCoder:(NSCoder *)aCoder  //aCoder就是編碼器
{
    //編碼
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeObject:self.gender forKey:@"gender"];
    [aCoder encodeInteger:self.age forKey:@"age"];
//    [aCoder encodeObject:self.dog forKey:@"dog"];     //在dog的那邊也要歸檔

}


#pragma mark --------------進行反編碼
- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super init];
    if (self) {
        self.name  = [aDecoder decodeObjectForKey:@"name"];
        self.gender = [aDecoder decodeObjectForKey:@"gender"];
        self.age = [aDecoder decodeIntegerForKey:@"age" ];
//        self.dog = [aDecoder decodeObjectForKey:@"dog"];     //在dog的那邊也要反歸檔
    }

    return self;
}

@end