//数据持久化的本质:将数据读取成文件保存在本地. 沙盒机制就是系统针对于每一个程序在本地生成的文件夹(名字随机生成), 对于不同的应用程序, 不能访问其他应用程序沙盒内的内容, 对于该应用程序内容起到保护作用:1 Documents:用来存储长久保存的数据 2 xxx.app:应用程序的包, 包含应用程序加载所需的所有资源(readonly只读, 不可修改), 平时使用的NSBundle就是该包 3 Library: 1) Caches:本地缓存, 存储想暂时保存的数据(Videos, Musics, Images) 比如:下载的视频, 音频, 图片都存储在该文件夹下 2) Preferences:存储用户的偏好设置, 比如程序是否是第一次启动 4 tmp:存储还未下载完的视频, 音频, 当下载完后, 将文件转移到Caches文件夹下 #import "WYLReadAndWriteViewController.h" #import "WYLArchive.h" @interface WYLReadAndWriteViewController ()<UITextFieldDelegate> @end @implementation WYLReadAndWriteViewController - (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. self.view.backgroundColor = [UIColor whiteColor]; self.navigationItem.title = @"文件读写"; UITextField *textField = [[UITextField alloc]initWithFrame:CGRectMake(40, 84, 220, 40)]; textField.tag = 100; textField.placeholder = @"请输入内容"; textField.delegate = self; textField.borderStyle = UITextBorderStyleRoundedRect; [self.view addSubview:textField]; [textField release]; UITextField *textField2 = [[UITextField alloc]initWithFrame:CGRectMake(40, 174, 220, 40)]; textField2.tag = 101; textField2.placeholder = @"显示上一个输入框的内容"; textField2.delegate = self; textField2.borderStyle = UITextBorderStyleRoundedRect; [self.view addSubview:textField2]; [textField2 release]; UIButton *writeButton = [UIButton buttonWithType:UIButtonTypeSystem]; writeButton.frame = CGRectMake(45, 260, 60, 30); [writeButton setTitle:@"写入" forState:UIControlStateNormal]; [writeButton addTarget:self action:@selector(write:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:writeButton]; UIButton *readButton = [UIButton buttonWithType:UIButtonTypeSystem]; readButton.frame = CGRectMake(190, 260, 60, 30); [readButton setTitle:@"读取" forState:UIControlStateNormal]; [readButton addTarget:self action:@selector(read:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:readButton]; UIButton *push = [UIButton buttonWithType:UIButtonTypeSystem]; push.frame = CGRectMake(120, 310, 60, 30); [push setTitle:@"push" forState:UIControlStateNormal]; [push addTarget:self action:@selector(push:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:push]; } - (NSString *)getFilePath { //用来获取指定文件夹的路径:<#NSSearchPathDirectory directory#>:指定的文件夹;<#NSSearchPathDomainMask domainMask#>:设置查找的域, 我们自己的文件都是存储在永华域的;<#BOOL expandTilde#>:是否使用详细路径(绝对路径) 因为最初该方法是使用与MAC OS下的, 而对于电脑系统来说, 可能会存储多个用户, 所以获取到得用户可能有多个, 所以返回值类型是数组, 但是对于iOS下, 就要只有一个用户, 所以数组中只有一个元素 /* NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]; //2)拼接上要存储文件的路径 NSString *newFilePath = [documentsPath stringByAppendingPathComponent:@"aa.txt"]; NSLog(@"%@", newFilePath); */ NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]; NSString *newPath = [filePath stringByAppendingPathComponent:@"test.txt"]; NSLog(@"%@", newPath); return newPath; } - (void)read:(UIButton *)button { //每次写入都会将之前的内容覆盖掉, 若想保留之前的数据, 需要讲之前的数据读出, 然后将要存储的数据拼接在一起, 一起存入 /* NSString *newFilePath = [self getFilePath]; NSError *error = nil; NSString *content = [NSString stringWithContentsOfFile:newFilePath encoding:NSUTF8StringEncoding error:&error]; UITextField *tf = (UITextField *)[self.view viewWithTag:101]; tf.text = content; */ //字符串从本地读取 /* NSString *filePath = [self getFilePath]; NSString *content = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil]; UITextField *tf = (UITextField *)[self.view viewWithTag:101]; tf.text = content; */ //数组从本地文件读取 NSString *filePath = [self getFilePath]; // NSArray *arr = [NSArray arrayWithContentsOfFile:filePath]; //从字典从本地读取 NSDictionary *dic = [NSDictionary dictionaryWithContentsOfFile:filePath]; UITextField *tf = (UITextField *)[self.view viewWithTag:100]; UITextField *tf1 = (UITextField *)[self.view viewWithTag:101]; tf.text = dic[@"tf2"]; tf1.text = dic[@"tf1"]; } //文件读写暂时只支持:NSString, NSArray, NSDictionary, NSData, 以及他们的子类.写入文件:writeToFile:(这是对象调用的方法), 读取文件:每一个类自带的能够根据路径创建对象的方法:[类名 类WithContentsOfFile]; 字符串:[NSString stringWithContentsOfFile], 数组:[NSArray arrayWithContentsOfFile], 字典:[NSDictionary dictionaryWithContentsOfFile], 二进制流:[NSData dataWithContentsOfFile],(牢牢谨记:对于数组, 字典这样的容器类, 内部的成员也必须是能够实现文件读写的八大类之一) - (void)write:(UIButton *)button { //写入时, 将第一个输入框中的文字, 写入到本地文件 //1 获取存储的内容 UITextField *tf = (UITextField *)[self.view viewWithTag:100]; NSString *content = tf.text; //2 获取到所要存储的文件路径 //1)获取Documents文件夹路径 NSString *newFilePath = [self getFilePath]; //3 将内容存储到指定文件路径 // NSError *error = nil; //字符串写入本地文件 // BOOL isSucceed = [content writeToFile:newFilePath atomically:YES encoding:NSUTF8StringEncoding error:&error]; //数组写入本地文件 UITextField *tf2 = (UITextField *)[self.view viewWithTag:101]; NSString *content1 = tf2.text; // NSArray *arr = @[content, content1]; // BOOL isSucceed = [arr writeToFile:newFilePath atomically:YES]; //字典写入本地文件 NSDictionary *dic = @{@"tf1": content, @"tf2": content1}; BOOL isSucceed = [dic writeToFile:newFilePath atomically:YES]; NSLog(@"%d", isSucceed); } - (void)push:(UIButton *)button { WYLArchive *archivieVC = [[WYLArchive alloc]init]; [self.navigationController pushViewController:archivieVC animated:YES]; } - (BOOL)textFieldShouldReturn:(UITextField *)textField { [textField resignFirstResponder]; return YES; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // 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 #import "WYLArchive.h" #import "Person.h" @interface WYLArchive ()<UITextFieldDelegate> @end @implementation WYLArchive - (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. self.view.backgroundColor = [UIColor whiteColor]; self.navigationItem.title = @"归档与反归档"; UITextField *textField = [[UITextField alloc]initWithFrame:CGRectMake(40, 84, 220, 40)]; textField.tag = 100; textField.placeholder = @"请输入内容"; textField.borderStyle = UITextBorderStyleRoundedRect; textField.delegate = self; [self.view addSubview:textField]; [textField release]; UITextField *textField2 = [[UITextField alloc]initWithFrame:CGRectMake(40, 174, 220, 40)]; textField2.tag = 101; textField2.placeholder = @"显示上一个输入框的内容"; textField2.borderStyle = UITextBorderStyleRoundedRect; textField2.delegate = self; [self.view addSubview:textField2]; [textField2 release]; UIButton *fileButton = [UIButton buttonWithType:UIButtonTypeSystem]; fileButton.frame = CGRectMake(45, 260, 60, 30); [fileButton setTitle:@"归档" forState:UIControlStateNormal]; [fileButton addTarget:self action:@selector(file:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:fileButton]; UIButton *archiveButton = [UIButton buttonWithType:UIButtonTypeSystem]; archiveButton.frame = CGRectMake(190, 260, 60, 30); [archiveButton setTitle:@"反归档" forState:UIControlStateNormal]; [archiveButton addTarget:self action:@selector(archive:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:archiveButton]; } - (NSString *)getPath { //获得文件夹的路径 /* NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]; NSString *newPath = [filePath stringByAppendingPathComponent:@"archive"]; return newPath; */ NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]; NSString *newPath = [path stringByAppendingPathComponent:@"archiver"]; return newPath; } - (void)file:(UIButton *)button { //获取输入框的内容 UITextField *tf1 = (UITextField *)[self.view viewWithTag:100]; UITextField *tf2 = (UITextField *)[self.view viewWithTag:101]; /* //封装成Person对象 Person *person = [[Person alloc] initWithName:tf1.text gender:tf2.text age:18]; //1 创建归档对象 NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; //2 归档 [archiver encodeObject:person forKey:@"person"]; [person release]; //3 结束归档, 当结束归档之后, 再归档无效 [archiver finishEncoding]; [archiver release]; //4 data写入文件 [data writeToFile:[self getPath] atomically:YES]; */ Person *person = [[Person alloc] initWithName:tf1.text gender:tf2.text age:18]; NSMutableData *data = [NSMutableData data]; NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data]; [archiver encodeObject:person forKey:@"archiver"]; [person release]; [archiver finishEncoding]; [archiver release]; [data writeToFile:[self getPath] atomically:YES]; } - (void)archive:(UIButton *)button { /* //1 初始化NSMutableData对象 NSMutableData *data = [NSMutableData dataWithContentsOfFile:[self getPath]]; //2 创建一个反归档对象 NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; //3 反归档 Person *person = [unarchiver decodeObjectForKey:@"person"]; //4 结束反归档 [unarchiver finishDecoding]; [unarchiver release]; */ NSMutableData *data = [NSMutableData dataWithContentsOfFile:[self getPath]]; NSKeyedUnarchiver *unarchive = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; Person *person = [unarchive decodeObjectForKey:@"archiver"]; [unarchive finishDecoding]; [unarchive release]; UITextField *tf1 = (UITextField *)[self.view viewWithTag:100]; UITextField *tf2 = (UITextField *)[self.view viewWithTag:101]; tf1.text = person.gender; tf2.text = person.name; } - (BOOL)textFieldShouldReturn:(UITextField *)textField { [textField resignFirstResponder]; return YES; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // 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
时间: 2024-10-05 19:56:21