文件操作在我们开发过程中或多或少都会遇到，我一般不会去记这些，每次使用的时候都要去查询下，有点麻烦，今天索性记录下，方便查找！

1. 写文件（保存文件）

    //保存文件
    - (void)writeFile {
        NSString *lastDir = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject] stringByAppendingPathComponent:@"cadLocalDir"];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        if ([fileManager fileExistsAtPath:lastDir]) {
            NSLog(@"存在");
        } else {
            NSLog(@"文件夹不存在");
            //注意：如果在某个文件夹下写文件，如果文件夹不存在，无法写成功
            BOOL isSuccess = [fileManager createDirectoryAtPath:lastDir withIntermediateDirectories:YES attributes:nil error:nil];
            if (isSuccess) {
                NSLog(@"success");
            } else {
                NSLog(@"fail");
            }
        }
        
        NSString *aPath = [lastDir stringByAppendingPathComponent:@"d.txt"];
        NSString *bPath = [lastDir stringByAppendingPathComponent:@"e.txt"];
        NSString *cPath = [lastDir stringByAppendingPathComponent:@"f.txt"];
       
        // 写入文件 注意：写文件时，如果文件名不存在，会自动创建
        NSString *a = @"哈哈哈哈哈写入文件";
        BOOL isA = [a writeToFile:aPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
        if (isA) NSLog(@"哈哈哈哈哈写入文件成功");
        NSString *b = @"哈哈哈哈哈写入文件";
        BOOL isB = [b writeToFile:bPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
        if (isB) NSLog(@"哈哈哈哈哈写入文件成功");
        NSString *c = @"哈哈哈哈哈写入文件";
        BOOL isC = [c writeToFile:cPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
        if (isC) NSLog(@"哈哈哈哈哈写入文件成功");
    }
   

2. 查找文件

    //获取文件数据
    - (void)getFileData {
        NSString *lastDir = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject] stringByAppendingPathComponent:@"cadLocalDir"];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        if (![fileManager fileExistsAtPath:lastDir]) {
            //cadLocalDir文件不存在
            return;
        }
        //lastDir 为文件夹的路径
        NSDirectoryEnumerator *myDirectoryEnumerator = [fileManager enumeratorAtPath:lastDir];
        //用来存文件信息的数组
        NSMutableArray *fileInfosArr = [[NSMutableArray alloc] init];
        NSString *file;
        //遍历当前目录
        while ((file = [myDirectoryEnumerator nextObject])) {
            if ([[file pathExtension] isEqualToString:@"dwg"]) {
                //取得文件扩展名为.dwg的文件名
                NSString *filePath = [lastDir stringByAppendingPathComponent:file];
                MlgEFileInfo *fileInfo = [[MlgEFileInfo alloc] init];
                fileInfo.fileName = file; //文件名
                fileInfo.filePath = filePath; //文件路径
                NSError *error = nil;
                NSDictionary *fileAttributes = [fileManager attributesOfItemAtPath:filePath error:&error];
                if (fileAttributes) {
                    id creationDate, fileModDate;
                    //文件创建日期
                    if ((creationDate = [fileAttributes objectForKey:NSFileCreationDate])) {
                        if ([creationDate isKindOfClass:[NSDate class]]) {
                            fileInfo.fileCreationDate = creationDate;
                        }
                    }
                    //文件修改日期
                    if ((fileModDate = [fileAttributes objectForKey:NSFileModificationDate])) {
                        if ([fileModDate isKindOfClass:[NSDate class]]) {
                            fileInfo.fileModificationDate = fileModDate;
                        }
                    }
                }
                [fileInfosArr addObject:fileInfo];
            }
        }
        
        NSArray *sortedFileInfos = [fileInfosArr sortedArrayUsingComparator:^NSComparisonResult(MlgEFileInfo *obj1, MlgEFileInfo *obj2) {
            return [obj2.fileModificationDate compare:obj1.fileModificationDate]; //降序
        }];
        [self.dataSource removeAllObjects];
        [self.dataSource addObjectsFromArray:sortedFileInfos];
    }
   

3. 删除文件

       //删除CAD文件
       - (void)deleteCadFiel:(NSString *)filePath {
              NSFileManager *fileManager = [NSFileManager defaultManager];
          // 判断要删除的文件是否存在
          if ([fileManager fileExistsAtPath:filePath]) {
            NSLog(@"文件存在");
            // 删除
            BOOL isSuccess = [fileManager removeItemAtPath:filePath error:nil];
            NSLog(@"%@",isSuccess ? @"删除成功" : @"删除失败");
        } else {
            NSLog(@"文件不存在");
        }
    }