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iPhone开发【二十一】数据持久化小结之第2篇属性文件(.plist)

热度:183   发布时间:2016-04-25 06:14:10.0
iPhone开发【二十一】数据持久化总结之第2篇属性文件(.plist)

转载请注明出处,原文网址:http://blog.csdn.net/m_changgong/article/details/8269151 作者:张燕广

实现的功能:1)演示使用属性文件持久化数据。

关键词:数据持久化 属性文件 plist

1、新建一个Sigle View Application,命名为Persistence-file,工程结构如下


2、修改ViewController.xib,添加4个Label控件和4个TextField控件,如下:


3、修改ViewController.h,如下:

#define kFileName @"data.plist"#import <UIKit/UIKit.h>@interface ViewController : UIViewController@property(nonatomic,retain)IBOutlet UITextField *name;@property(nonatomic,retain)IBOutlet UITextField *gender;@property(nonatomic,retain)IBOutlet UITextField *age;@property(nonatomic,retain)IBOutlet UITextField *education;-(NSString *)dataFilePath;-(void)applicationWillResignActive:(NSNotification *)nofication;@end
注意,需要连接各个输出口

4、修改ViewController.m,如下:

#import "ViewController.h"@implementation ViewController@synthesize name,gender,age,education;#pragma mark - View lifecycle- (void)viewDidLoad{	// Do any additional setup after loading the view, typically from a nib.    [super viewDidLoad];    UIApplication *app = [UIApplication sharedApplication];    //订阅通知UIApplicationWillResignActiveNotification,进行数据保存操作    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillResignActive:) name:UIApplicationWillResignActiveNotification object:app];    //初始化数据    [self initData];}-(void)initData{    NSString *filePath = [self dataFilePath];    NSLog(@"filePath=%@",filePath);        //从文件中读取数据,首先判断文件是否存在    if([[NSFileManager defaultManager] fileExistsAtPath:filePath]){        NSArray *array = [[NSArray alloc]initWithContentsOfFile:filePath];        name.text = [array objectAtIndex:0];        gender.text = [array objectAtIndex:1];        age.text = [array objectAtIndex:2];        education.text = [array objectAtIndex:3];                [array release];    }}-(void)applicationWillResignActive:(NSNotification *)nofication{    NSMutableArray *array = [[NSMutableArray alloc]init];    [array addObject:name.text];    [array addObject:gender.text];    [array addObject:age.text];    [array addObject:education.text];    //将数据写入到文件dataFilePath中    [array writeToFile:[self dataFilePath] atomically:YES];    [array release];}//获得文件路径-(NSString *)dataFilePath{    //检索Documents目录    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);//备注1    NSString *documentsDirectory = [paths objectAtIndex:0];//备注2    return [documentsDirectory stringByAppendingPathComponent:kFileName];}- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Release any cached data, images, etc that aren't in use.}- (void)viewDidUnload{    [super viewDidUnload];    // Release any retained subviews of the main view.    // e.g. self.myOutlet = nil;    self.name = nil;    self.gender = nil;    self.age = nil;    self.education = nil;}-(void)dealloc{    [name release];    [gender release];    [age release];    [education release];}- (void)viewWillAppear:(BOOL)animated{    [super viewWillAppear:animated];}- (void)viewDidAppear:(BOOL)animated{    [super viewDidAppear:animated];}- (void)viewWillDisappear:(BOOL)animated{	[super viewWillDisappear:animated];}- (void)viewDidDisappear:(BOOL)animated{	[super viewDidDisappear:animated];}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{    // Return YES for supported orientations    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);}@end
备注1、备注2:

NSDocumentDirectory:常量,表明正在查找Documents目录的路径
NSUserDomainMask:常量,表面将搜索限制与当前应用程序的沙盒中,这样的话只能找到一个Documents目录,因为每个应用程序沙盒中只有一个Documents目录,所以备注2中从paths中取第一个即为当前应用程序的Documents目录的路径

5、编译、运行,在TextField中输入内容,然后退出Simulator,进行测试:


6、通过上一篇对IOS应用程序沙盒的的介绍,本工程属性文件data.plist,保存的位置是:

/Users/duobianxing/Library/Application Support/iPhone Simulator/5.0/Applications/88528A36-00CB-4900-9762-1FD5D6AC8595/Documents


7、总结:

1)可以简单保存静态数据,但是无法将自定义对象序列化到属性列表中

2)该持久化方法与上一篇中介绍的NSUserDefaults实质上都是将数据写入到.plist属性文件中,区别是文件保存的位置不同。

需要源码的网友请留言哦

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