NSFileManager

本小节知识点:

1. 【理解】NSFileManager介绍
2. 【理解】NSFileManager用法(常见的判断)
3. 【理解】NSFileManager的文件访问
4. 【理解】NSFileManager的文件操作

1.NSFileManager介绍

• 什么是NSFileManager

  • 顾名思义, NSFileManager是用来管理文件系统的
  • 它可以用来进行常见的文件\文件夹操作

• NSFileManager使用了单例模式

  • 使用defaultManager方法可以获得那个单例对象

    [NSFileManager defaultManager]
    

2.NSFileManager用法

• - (BOOL)fileExistsAtPath:(NSString *)path;
  • path这个文件\文件夹是否存在

    NSFileManager *manager = [NSFileManager defaultManager];
    // 可以判断文件
    BOOL flag = [manager fileExistsAtPath:@"/Users/LNJ/Desktop/lnj.txt"];
    NSLog(@"flag = %i", flag);
    // 可以判断文件夹
    flag = [manager fileExistsAtPath:@"/Users/LNJ/Desktop/未命名文件夹"];
    NSLog(@"flag = %i", flag);

• - (BOOL)fileExistsAtPath:(NSString )path isDirectory:(BOOL )isDirectory;
  • path这个文件\文件夹是否存在, isDirectory代表是否为文件夹

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL directory = NO;
    BOOL flag = [manager fileExistsAtPath:@"/Users/LNJ/Desktop/未命名文件夹" isDirectory:&directory];
    NSLog(@"flag = %i, directory = %i", flag, directory);

• - (BOOL)isReadableFileAtPath:(NSString *)path;

  • path这个文件\文件夹是否可读

• - (BOOL)isWritableFileAtPath:(NSString *)path;

  • path这个文件\文件夹是否可写
  • 系统目录不允许写入

• - (BOOL)isDeletableFileAtPath:(NSString *)path;

  • path这个文件\文件夹是否可删除
  • 系统目录不允许删除

3.NSFileManager的文件访问

• - (NSDictionary )attributesOfItemAtPath:(NSString )path error:(NSError **)error;
  • 获得path这个文件\文件夹的属性

    NSFileManager *manager = [NSFileManager defaultManager];
    NSDictionary *dict = [manager attributesOfItemAtPath:@"/Users/LNJ/Desktop/lnj.txt" error:nil];
    NSLog(@"dit = %@", dict);

• - (NSArray )contentsOfDirectoryAtPath:(NSString )path error:(NSError **)error;

  • 获得path的当前子路径

• - (NSData )contentsAtPath:(NSString )path;

  • 获得文件内容

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager contentsOfDirectoryAtPath:@"/Users/LNJ/Desktop/" error:nil];
    NSLog(@"paths = %@", paths);

• - (NSArray )subpathsAtPath:(NSString )path;
• - (NSArray )subpathsOfDirectoryAtPath:(NSString )path error:(NSError **)error;
  • 获得path的所有子路径

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager subpathsAtPath:@"/Users/LNJ/Desktop/"];
    NSLog(@"paths = %@", paths);

4.NSFileManager的文件操作

• - (BOOL)copyItemAtPath:(NSString )srcPath toPath:(NSString )dstPath error:(NSError **)error;

  • 拷贝

• - (BOOL)moveItemAtPath:(NSString )srcPath toPath:(NSString )dstPath error:(NSError **)error;

  • 移动(剪切)

• - (BOOL)removeItemAtPath:(NSString )path error:(NSError *)error;

  • 删除

• - (BOOL)createDirectoryAtPath:(NSString )path withIntermediateDirectories:(BOOL)createIntermediates attributes:(NSDictionary )attributes error:(NSError **)error;

  • 创建文件夹(createIntermediates为YES代表自动创建中间的文件夹)

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createDirectoryAtPath:@"/Users/LNJ/Desktop/test" withIntermediateDirectories:YES attributes:nil error:nil];
    NSLog(@"flag = %i", flag);

• - (BOOL)createFileAtPath:(NSString )path contents:(NSData )data attributes:(NSDictionary *)attr;
  • 创建文件(NSData是用来存储二进制字节数据的)

    NSString *str = @"lnj";
    NSData  *data = [str dataUsingEncoding:NSUTF8StringEncoding];
    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createFileAtPath:@"/Users/LNJ/Desktop/abc.txt" contents:data attributes:nil];
    NSLog(@"flag = %i", flag);