NSURL故障导致NSFileHandle [英] NSFileHandle from NSURL failure

问题描述

我正在尝试将一些数据写入文件.我可以从文件对话框中获取NSURL，并且获得的NSURL具有以下值

I'm trying to write some data to a file. I am able to obtain an NSURL from a file dialog and the NSURL obtained has the following value

file:///Users/brad/Documents/2016-05-04-06-53-35.csv

我的代码执行以下操作:

My code does the following:

NSURL*  myFile = [panel URL]; // is     file:///Users/brad/Documents/2016-05-04-06-53-35.csv
NSError *error = nil;   

NSFileHandle *myFileHandle = [NSFileHandle fileHandleForWritingToURL:myFile error:&error];
NSLog(@"%@",error);

if (myFileHandle)
{
  ... // do something 
} 
else 
{
 NSLog(@"File operation failed");
}

我收到一条错误消息，指出以下内容

I get an error which indicates the following

 Error Domain=NSCocoaErrorDomain Code=2 "(null)" UserInfo={NSFilePath=/Users/brad/Documents/

myFileHandle也为零.

Also myFileHandle is nil.

有任何线索吗?

推荐答案

请参见NSFileHandle fileHandleForWritingToURL:error:的文档.如果文件不存在，您将返回nil.

See the documentation for NSFileHandle fileHandleForWritingToURL:error:. You get back nil if the file doesn't already exist.

使用NSFileManager首先检查文件是否存在.如果不是，请使用NSFileManager createFileAtPath:contents:attributes:创建一个空文件.

Use NSFileManager to first check if the file exists or not. If not, use NSFileManager createFileAtPath:contents:attributes: to create an empty file.

NSURL *myFile = [panel URL];
if (![[NSFileManager defaultManager] fileExistsAtPath:[myFile path]]) {
    [[NSFileManager defaultManager] createFileAtPath:[myFile path] contents:[NSData data] attributes:nil];
}

NSError *error = nil;   

NSFileHandle *myFileHandle = [NSFileHandle fileHandleForWritingToURL:myFile error:&error];

这篇关于NSURL故障导致NSFileHandle的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！