IOS 數據持久化(歸檔與反歸檔)

數據持久化，實際上就是將數據存放到網絡或者硬盤上，這裡是存儲到本地的硬盤上，應用程序的本地硬盤是沙盒，沙盒實際上就是一個文件夾，它下面有4個文件夾。分別是Documents，Library，APP包和tmp文件夾

Documents裡面主要是存儲用戶長期使用的文件，

Library裡面又有Caches和Preferences文件夾，

(1)Caches裡面存放的是臨時的文件，緩存。

(2)Preferences裡面存放的是偏好設置。比如:程序是否是第一次啟動

tmp裡面也是臨時的文件，不過和Caches還有區別，

APP包裡面是編譯後的一些文件，包不能修改。

一.首先創建一個Person類

.h文件

#import

//如果要對一個類的對象實現歸檔操作,必須讓該類服從NSCoding協議

@interface Person :NSObject

@property (nonatomic,copy) NSString *name;

@property (nonatomic,copy) NSString *gender;

@property (nonatomic,assign) NSInteger age;

- (id)initWithName:(NSString *)name gender:(NSString *)gender age:(NSInteger)age;

@end

.m文件

#import"Person.h"

@implementation Person

- (id)initWithName:(NSString *)name gender:(NSString *)gender age:(NSInteger)age

{

self = [superinit];

if (self) {

//1.當對象為字符串, 數組, 字典, 集合時, 屬性的語義特性聲明為copy

//2.定義完屬性再給實例變量賦值時, 要使用setter方法

//3.一定要注意屬性的內存管理

self.name = name;

self.gender = gender;

self.age = age;

}

return self;

}

//當對一個對象歸檔時,會調用對象的該方法,為該對象自己的實力變量進行歸檔

- (void)encodeWithCoder:(NSCoder *)aCoder

{

[aCoderencodeObject:_nameforKey:@"name"];

[aCoderencodeObject:_genderforKey:@"gender"];

[aCoderencodeObject:@(_age)forKey:@"age"];

}

//當對一個對象反歸檔時,會調用對象的該方法,為該對象的實例變量進行反歸檔

- (id)initWithCoder:(NSCoder *)aDecoder

{

self = [superinit];

if (self) {

self.name = [aDecoder decodeObjectForKey:@"name"];

self.gender = [aDecoder decodeObjectForKey:@"gender"];

self.age = [[aDecoderdecodeObjectForKey:@"age"]integerValue];

}

return self;

}

- (void)dealloc

{

self.name =nil;

self.gender =nil;

[superdealloc];

}

@end

二:主程序中的歸檔與反歸檔(.m文件)

這裡面為了易於理解,創建TextFiled 以及其他控件一起寫出來了

#import "SecondViewController.h"

#import "Person.h"

@interfaceSecondViewController ()

@end

@implementation SecondViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

self = [superinitWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

// Custom initialization

}

returnself;

}

- (void)viewDidLoad

{

[superviewDidLoad];

[selfcustomizeNavigationControl];

// Do any additional setup after loading the view.

self.view.backgroundColor = [UIColorwhiteColor];

//創建視圖控件

//textFile1

UITextField *firstFiled = [[UITextFieldalloc] initWithFrame:CGRectMake(30,94, 260, 30)];

firstFiled.delegate =self;

firstFiled.tag =100;

firstFiled.placeholder =@"請輸入內容";

firstFiled.autocorrectionType =UITextAutocorrectionTypeNo;

firstFiled.borderStyle =UITextBorderStyleRoundedRect;

[self.viewaddSubview:firstFiled];

[firstFiled release];

//textFile2

UITextField *secondFiled = [[UITextFieldalloc] initWithFrame:CGRectMake(30,154, 260, 30)];

secondFiled.delegate =self;

secondFiled.tag =101;

secondFiled.autocorrectionType =UITextAutocorrectionTypeNo;

secondFiled.placeholder =@"顯示上一個輸入框的內容";

secondFiled.borderStyle =UITextBorderStyleRoundedRect;

[self.viewaddSubview:secondFiled];

[secondFiled release];

//writeButton

UIButton *pigeonholeButton = [UIButtonbuttonWithType:UIButtonTypeCustom];

pigeonholeButton.frame =CGRectMake(30, 214,100, 30);

[pigeonholeButton setTitle:@"歸檔"forState:UIControlStateNormal];

[pigeonholeButton setTitleColor:[UIColorblueColor] forState:UIControlStateNormal];

[pigeonholeButton addTarget:self action:@selector(pigeonholeClick:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:pigeonholeButton];

//readButton

UIButton *againstPigeonholeButton = [UIButtonbuttonWithType:UIButtonTypeCustom];

againstPigeonholeButton.frame =CGRectMake(190, 214, 100, 30);

[againstPigeonholeButtonsetTitle:@"反歸檔"forState:UIControlStateNormal];

[againstPigeonholeButtonsetTitleColor:[UIColorblueColor] forState:UIControlStateNormal];

[againstPigeonholeButton addTarget:self action:@selector(againstPigeonholeClick:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:againstPigeonholeButton];

}

//歸檔

- (void)pigeonholeClick:(UIButton *)pigeonholeBtn

{

//1.獲取輸入框的內容

UITextField *tf1 = (UITextField *)[self.viewviewWithTag:100];

UITextField *tf2 = (UITextField *)[self.viewviewWithTag:101];

//封裝成Person對象

Person *per = [[Personalloc] initWithName:tf1.textgender:tf2.text age:18];

//一.創建歸檔對象

NSMutableData *data = [NSMutableDatadata];

NSKeyedArchiver *archiver = [[NSKeyedArchiveralloc] initForWritingWithMutableData:data];

//二.歸檔

[archiver encodeObject:perforKey:@"Tsummer"];

//三.結束歸檔當結束歸檔之後再歸檔無效.

[archiver finishEncoding];

[per release];

[archiver release];

//四.data寫入文件

[data writeToFile:[selfgetFilePath] atomically:YES];

}

//反歸檔

- (void)againstPigeonholeClick:(UIButton *)againstPigeonholeBtn

{

//1.根據文件路徑初始化NSMutableData對象

NSMutableData *mData = [NSMutableDatadataWithContentsOfFile:[selfgetFilePath]];

//2.創建一個反歸檔對象

NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiveralloc] initForReadingWithData:mData];

//3.反歸檔

Person *per = [unarchiverdecodeObjectForKey:@"Tsummer"];

//4.結束反歸檔

[unarchiver finishDecoding];

[unarchiver release];

UITextField *tf1 = (UITextField *)[self.viewviewWithTag:100];

tf1.text = per.gender;

UITextField *tf2 = (UITextField *)[self.viewviewWithTag:101];

tf2.text = per.name;

NSLog(@"反歸檔");

}

//獲取文件路徑

- (NSString *)getFilePath

{

//1.先獲得Documents文件夾的路徑

NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES) firstObject];

//(2)拼接上文件路徑

NSString *newFilePath = [documentsPath stringByAppendingPathComponent:@"Tsummer.txt"];

NSLog(@"%@", newFilePath);

return newFilePath;

}

//定制navigationControl

- (void)customizeNavigationControl

{

self.navigationItem.title =@"歸檔與反歸檔";

}

- (BOOL)textFieldShouldReturn:(UITextField *)textField

{

[textField resignFirstResponder];

returnYES;

}

- (void)didReceiveMemoryWarning

{

[superdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

/*

#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

// Get the new view controller using [segue destinationViewController].

// Pass the selected object to the new view controller.

}

*/

@end