OC：文件的读写、复制、移动和删除

NSDocumentDirectory与NSDocumentationDirectory 的区别：

NSDocumentDirectory是指程序中对应的Documents路径，而NSDocumentionDirectory对应于程序中的Library/Documentation路径，这个路径是没有读写权限的，所以看不到文件生成。

获取写入路径：

- (NSString *)documentsDirectory {
    
    NSString *documentsDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    return documentsDirectory;
}

---

写入一

- (IBAction)write:(id)sender {
    
    NSString *txt = @"This is a book";
    NSString *filePath = [[self documentsDirectory] stringByAppendingPathComponent:@"MZString.txt"];
    BOOL isSuccess = [txt writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
    if (isSuccess) {
        NSLog(@"Write Succeed");
    } else {
        NSLog(@"Write Failed");
    }
    
    // 追加写入（不覆盖原先数据)
    NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];
    [handle seekToEndOfFile]; // 移动到文件的末尾
    [handle writeData:[@"以下为追加写入😄" dataUsingEncoding:NSUTF8StringEncoding]]; // 在文件末尾写入数据
    [handle closeFile]; // 关闭
    
    NSLog(@"%@", filePath);
    
    // 获取文件总长度
    NSFileManager *manager = [NSFileManager defaultManager];
    NSDictionary *dict = [manager attributesOfItemAtPath:filePath error:nil]; // 返回给定路径item的属性
    long long length = [[dict objectForKey:NSFileSize] longLongValue];
    NSLog(@"%lld", length);
}

// 沙盒路径
- (NSString *)documentsDirectory {
    
    NSString *documentsDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    return documentsDirectory;
}

写入二

- (IBAction)write:(id)sender {
    
    NSLog(@"%@", [self folderPath]);
    
    // 检查缓存是否存在
    NSString *filePath = [[self folderPath] stringByAppendingPathComponent:@"File"];
    id contents = [self getContentsAtPath:filePath];
    if (contents) {
        NSLog(@"😄缓存存在：%@", contents);
        return;
    }
    
    NSString *txt = @"{\"data\":\"This is a book.\"}";
    
    [[NSFileManager defaultManager] createDirectoryAtPath:[self folderPath] withIntermediateDirectories:YES attributes:nil error:nil];
    
    // 写入的速度比较慢
//    [[NSFileManager defaultManager] createFileAtPath:filePath contents:[txt dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];
    [txt writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
}

// 沙盒路径
- (NSString *)documentsDirectory {
    
    NSString *documentsDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    return documentsDirectory;
}

// 存储路径
- (NSString *)folderPath {
    
    return [[self documentsDirectory] stringByAppendingPathComponent:@"MyCache"];
}

// 检查缓存是否存在
- (id)getContentsAtPath:(NSString *)path {
    
    // 指定路径不存在
    if ([path isKindOfClass:[NSNull class]] || !path || path.length == 0) {
        return nil;
    }
    
    NSData *data = [NSData dataWithContentsOfFile:path];
    if (data) {
        return [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves error:nil];
    }
    return nil;
}

---

移动

- (IBAction)move:(id)sender {
    
    NSString *filePath = [[self folderPath] stringByAppendingPathComponent:@"File"];
    NSString *contFilePath = [[self folderPath] stringByAppendingPathComponent:@"newFile"];
    
    NSFileManager *manager = [NSFileManager defaultManager];
    [manager moveItemAtPath:filePath toPath:contFilePath error:nil];
}

---

复制

- (IBAction)copy:(id)sender {
    
    NSString *filePath = [[self folderPath] stringByAppendingPathComponent:@"newFile"];
    NSString *CopyFilePath = [[self folderPath] stringByAppendingPathComponent:@"CopedFile"];
    
    NSFileManager *manager = [NSFileManager defaultManager];
    [manager copyItemAtPath:filePath toPath:CopyFilePath error:nil];
}

---

删除

- (IBAction)delete:(id)sender {
    
    NSString *file = [[self folderPath] stringByAppendingPathComponent:@"CopedFile"];
    
    NSFileManager *manager = [NSFileManager defaultManager];
    [manager removeItemAtPath:file error:nil];
}