iOS学习笔记-----文件操作

来源：互联网发布：java opencv 二值化编辑：程序博客网时间：2024/06/09 23:53

一.沙盒

1.沙盒的概念

(1)iOS中每个App应用程序都有一个单独封闭的文件夹,这个文件夹称为沙盒 (sandbox)
(2)沙盒目录用来存放App的本地文件,例如:音频、视频、图片文件……..
(3)当前App应用程序没权限访问其他App的沙盒。(更安全)
(4)沙盒目录中有如下子目录:
- Documents :存放长期使用的文件.
- Library :系统存放文件.
- tmp :临时文件,App重启时,该目录下的文件清空.

2.获取沙盒的路径

文件是需要通过路径去访问.

        // 沙盒路径---方法一        NSString *sandBoxPath = NSHomeDirectory();        NSLog(@"沙盒路径:%@", sandBoxPath);        // 拼接路径方法一        NSString *path1 = [sandBoxPath stringByAppendingString:@"/Documents"];        NSLog(@"path1:%@", path1);        // 拼接路径方法二        NSString *path2 = [sandBoxPath stringByAppendingPathComponent:@"Documents"];        NSLog(@"path2:%@", path2);        // 沙盒路径---方法二,此方法不仅在iOS开发可以用,在mac开发下也可用        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);        NSLog(@"paths:%@", paths);

二.文件操作

1.文件的创建

NSFileManager *fileManager = [NSFileManager defaultManager];       // NSHomeDirectory 在命令行模式是当前用户主目录        NSString *homePath = NSHomeDirectory();        NSLog(@"homePath:%@", homePath);        NSString *str = @"好好学习,天天向上!";        // 拼接路径        NSString *filePath = [homePath stringByAppendingPathComponent:@"Desktop/file.txt"];        // 把NSString -----> NSData        NSData *dataContents = [str dataUsingEncoding:NSUTF8StringEncoding];        // 把NSData写入硬盘        // 实例化NSFileManager        // 创建文件所调用的方法        BOOL success = [fileManager createFileAtPath:filePath contents:dataContents attributes:nil];        if (success) {            NSLog(@"文件创建成功或者已经存在");        }

2.文件夹的创建

      // 绘制路径        NSString *dirPath = [homePath stringByAppendingPathComponent:@"Desktop/hua/yeah/ok"];     NSFileManager *fileManager = [NSFileManager defaultManager];            success = [fileManager createDirectoryAtPath:dirPath withIntermediateDirectories:YES attributes:nil error:nil];        if (success) {            NSLog(@"文件夹创建成功或者已经存在");        }

3.读取文件

        NSFileManager *fileManager = [NSFileManager defaultManager];            NSString *filePath2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/file.txt"];        NSData *fileData = [fileManager contentsAtPath:filePath2];        NSString *str2 = [[NSString alloc] initWithData:fileData encoding:NSUTF8StringEncoding];        NSLog(@"str2:%@", str2);

4.剪切文件

        NSFileManager *fileManager = [NSFileManager defaultManager];            NSString *sourcePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/file.txt"];        NSString *dirPath2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/hua/file.txt"];        BOOL success = [fileManager moveItemAtPath:sourcePath toPath:dirPath2 error:nil];        if (success) {            NSLog(@"文件剪切成功");        }

5.复制文件如果目标文件已经存在,则剪切和复制都不会成功

        NSFileManager *fileManager = [NSFileManager defaultManager];            NSString *dirPath3 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/file.txt"];        NSString *sourcePath2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/hua/file.txt"];        BOOL success = [fileManager copyItemAtPath:sourcePath2 toPath:dirPath3 error:nil];        if (success) {            NSLog(@"文件复制成功");        }*/

6.删除文件

        NSFileManager *fileManager = [NSFileManager defaultManager];            NSString *sourcePath3 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/file.txt"];        BOOL success =[fileManager removeItemAtPath:sourcePath3 error:nil];        if (success) {            NSLog(@"文件删除成功");        }

7.读取文件属性

        NSFileManager *fileManager = [NSFileManager defaultManager];            NSString *sourcePath4 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/hua/file.txt"];        NSDictionary *dic = [fileManager attributesOfItemAtPath:sourcePath4 error:nil];        NSLog(@"dic:%@", dic);

三.文件读写

      // 1.NSString 写入文件        NSString *str = @"同学们太棒了";        NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/string.txt"];        // atomically:控制重写文件是否保护,YES:会确认写入的安全性,NO:会直接覆盖源文件        BOOL success =[str writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];        if (success) {            NSLog(@"写入数据成功");        }        // 2.NSArray 写入文件        NSArray *array = @[@"huang", @"rui", @"hua"];        NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/array.plist"];        BOOL success = [array writeToFile:path atomically:YES];        if (success) {            NSLog(@"写入数据成功");        }        // 3.NSDictionary 写入文件        NSDictionary *dic = @{                              @"key" : @"value",                              @"liuzhengyi" : @"xueba",                              @"lilong" : @"jingshenhao",                              @"tangyupeng" : @"nanshen"                              };        NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/dictionary.plist"];        BOOL success = [dic writeToFile:path atomically:YES];        if (success) {            NSLog(@"写入数据成功");        }         */        // 4.读取文件        // 读取文本        NSString *path1 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/string.txt"];        NSString *str = [NSString stringWithContentsOfFile:path1 encoding:NSUTF8StringEncoding error:nil];        NSLog(@"str:%@", str);        // 读取数组文件(plist)        NSString *path2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/array.plist"];        NSArray *array = [NSArray arrayWithContentsOfFile:path2];        NSLog(@"array:%@", array);        // 读取字典文件(plist);        NSString *path3 = [NSHomeDirectory() stringByAppendingPathComponent:@"Desktop/dictionary.plist"];        NSDictionary *dic = [NSDictionary dictionaryWithContentsOfFile:path3];        NSLog(@"dic:%@", dic);

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