iOS 数据持久化一－属性列表 Plist

iOS中有五种持久化数据的方式：属性列表、对象归档、NSUserDefault、SQLite3和Core Data

本文章讲述通过属性列表的方式持久化数据，这个方法也是我们平时最经常用到的方式。比如应用程序的配置和个性化的设置，一般都是通过属性列表（properties list） plist文件来存储和读取的。

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FOUNDATION_EXPORT NSArray *NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory directory, NSSearchPathDomainMask domainMask, BOOL expandTilde);

这个函数的作用：创建一个目录搜索路径的列表。

创建一个路径字符串列表指定域中指定的目录。列表中的顺序，你应该搜索目录。

PS：

通过此方法返回的目录可能不存在。这种方法只是给你请求目录的适当位置。根据应用的需求，它可能是开发者创建合适的目录或者在任何两者之间。
下面是一个把数据以plist的形式保存到本地的自定义类

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//

// Plist.h

// PlistDemo

//

// Created by swplzj on 13-11-20.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import <Foundation/Foundation.h>

@interface Plist : NSObject

- (void)modifyData:(NSString *)dataKey Value:(NSString *)dataValue;

- (void)deleteDataWithDataKey:(NSString *)key;

@end

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//

// Plist.m

// PlistDemo

//

// Created by swplzj on 13-11-20.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import "Plist.h"

@implementation Plist

- (id)init

{

if (self = [super init]) {

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

//获取完整路径

NSString *documentsDirectory = [paths objectAtIndex:0];

NSLog(@"homeDirectory = %@", documentsDirectory);

NSString *plistPath = [documentsDirectory stringByAppendingPathComponent:@"student.plist"];

//判断是否已经创建文件

if ([[NSFileManager defaultManager] fileExistsAtPath:plistPath]) {

NSLog(@"student.plist文件已经存在！");

}else {

//plist文件没有被创建

NSMutableDictionary *rootDic = [[NSMutableDictionary alloc] init];

NSMutableDictionary *subDic = [[NSMutableDictionary alloc] init];

[rootDic setObject:subDic forKey:@"student"];

[subDic release];

//写入到文件

[rootDic writeToFile:plistPath atomically:YES];

[rootDic release];

}

}

return self;

}

//把数据写入到plist文件中

- (void)modifyData:(NSString *)dataKey Value:(NSString *)dataValue

{

//获取路径

NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"student.plist"];

NSMutableDictionary *rootDic = [[[NSMutableDictionary alloc] initWithContentsOfFile:path] mutableCopy];

NSMutableDictionary *studentInfo = [rootDic objectForKey:@"student"];

NSString *name = [studentInfo objectForKey:dataKey];

name = dataValue;

[studentInfo setValue:name forKey:dataKey];

//写入到文件

[rootDic writeToFile:path atomically:YES];

NSLog(@"Key - Value: %@ - %@",dataKey, dataValue );

[rootDic release];

}

//根据key来删除某一行的数据

- (void)deleteDataWithDataKey:(NSString *)key

{

//获取路径

NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"student.plist"];

NSMutableDictionary *rootDic = [[[NSMutableDictionary alloc] initWithContentsOfFile:path] mutableCopy];

NSMutableDictionary *studentInfo = [rootDic objectForKey:@"student"];

[studentInfo removeObjectForKey:key];

NSLog(@"Delete data key - value: %@ - %@", key, [studentInfo objectForKey:key]);

[rootDic setValue:studentInfo forKey:@"student"];

//写入到文件

[rootDic writeToFile:path atomically:YES];

[rootDic release];

}

@end

在RootViewController里面的代码

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//

// RootViewController.m

// PlistDemo

//

// Created by swplzj on 13-11-20.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import "RootViewController.h"

#import "Plist.h"

@interface RootViewController ()

@property (retain, nonatomic) Plist *plistFile;

@property (retain, nonatomic) IBOutlet UITextField *keyTF;

@property (retain, nonatomic) IBOutlet UITextField *valueTF;

@property (retain, nonatomic) IBOutlet UITextField *deleteKeyTF;

@end

@implementation RootViewController

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

{

self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

// Custom initialization

}

return self;

}

- (void)viewDidLoad

{

[super viewDidLoad];

// Do any additional setup after loading the view from its nib.

_plistFile = [[Plist alloc] init];

}

- (void)didReceiveMemoryWarning

{

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

- (IBAction)addOrModifyBtnClicked:(id)sender {

if (![_keyTF.text isEqualToString:@""] && ![_valueTF.text isEqualToString:@""]) {

[_plistFile modifyData:_keyTF.text Value:_valueTF.text];

}

}

- (IBAction)deleteBtnClicked:(id)sender {

if (![_deleteKeyTF.text isEqualToString:@""]) {

[_plistFile deleteDataWithDataKey:_deleteKeyTF.text];

}

}

- (void)dealloc {

[_plistFile release];

[_keyTF release];

[_valueTF release];

[_deleteKeyTF release];

[super dealloc];

}

@end

效果





前往文件夹：

/Users/issuser/Library/Application Support/iPhone Simulator/6.1/Applications/A40F6B2C-002A-4797-B501-3ABCBE59723A/Documents











plist文件中的内容：











好了，这就是通过属性列表plist文件来达到数据持久化的目的。点击这里可以下载plistDemo代码