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
//3.一定要註意屬性的內存管理
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)
這裡面為瞭易於理解,創建TextFiled 以及其他控件一起寫出來瞭
#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