编写一个函数，实现递归删除指定路径下的所有文件

+ (void)deleteFiles:(NSString *)path { 
    // 1.判断文件还是目录      
    NSFileManager * fileManger = [NSFileManager defaultManager];
    BOOL isDir = NO;
    BOOL isExist = [fileManger fileExistsAtPath:path isDirectory:&isDir];
    if (isExist) {
        // 2.判断是不是目录      
        if (isDir) {
            NSArray * dirArray = [fileManger contentsOfDirectoryAtPath:path error:nil];
            NSString * subPath = nil;
                for (NSString * str in dirArray) {
                    subPath  = [path stringByAppendingPathComponent:str];
                    BOOL issubDir = NO;
                    [fileManger fileExistsAtPath:subPath isDirectory:&issubDir];
                    [self deleteFiles:subPath];
                }
        } else {
            NSLog(@"%@",path);
            [manager removeItemAtPath:filePath error:nil];
        } 
    } else {
        NSLog(@"你打印的是目录或者不存在"); 
    }
}