我正在尝试创建一个目录NSError*error=nil;NSString*BIDirectory=[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES)objectAtIndex:0]stringByAppendingPathComponent:@"BI"];BOOLisDir,flag=YES;//ifthedirectorydoesn'texistcreateit.if(!([[NSFileManagerdefaultManager]fileExistsAtPath:BIDirec