objective-c – 使用NSFileHandle进行文件读取/写入的示例

发布时间：2020-12-16 05:29:08 所属栏目：百科来源：网络整理

导读：有没有很好的例子来做文件读/写与块c与客观c？我是 Objective-c和iPhone API的新手,这里是我写的示例代码.有更好的方法吗？ -(void) performFileOperation{ @try { NSFileHandle *inputFileHandle; NSFileHandle *outputFileHandle; //check whether the out

有没有很好的例子来做文件读/写与块c与客观c？我是 Objective-c和iPhone API的新手,这里是我写的示例代码.有更好的方法吗？

-(void) performFileOperation
{
    @try {

        NSFileHandle *inputFileHandle;
        NSFileHandle *outputFileHandle;

        //check whether the output file exist,if not create a new one.
        NSFileManager *morphedFileManager;

        outputFileManager = [NSFileManager defaultManager];

        if ([outputFileManager fileExistsAtPath: self.outputFilePath ] == NO)
        {
            NSLog (@"Output file does not exist,creating a new one");
            [outputFileManager createFileAtPath: self.outputFilePath
                                        contents: nil
                                      attributes: nil];
        }

        NSData *inputDataBuffer;

        inputFileHandle = [NSFileHandle fileHandleForReadingAtPath: self.inputFilePath];

        NSAssert( inputFileHandle != nil,@"Failed to open handle for input file" );

        outputFileHandle  = [NSFileHandle fileHandleForReadingAtPath: self.outputFilePath];

        NSAssert( outputFileHandle != nil,@"Failed to open handle for output file" );

        @try{
            // seek to the start of the file
            [inputFileHandle seekToFileOffset: 0];
            [outputFileHandle seekToFileOffset: 0];

            while( (inputDataBuffer = [inputFileHandle readDataOfLength: 1024]) != nil )
            {
                [outputFileHandle writeData: [self.fileWrapper process: inputDataBuffer]];
            }
        }
        @catch (NSException *exception) {
            @throw;
        }
        @finally {
            [inputFileHandle closeFile];
            [outputFileHandle closeFile];
        }        
    }
    @catch (NSException *exception) {
        @throw;
    }
}

尝试写入时,我收到以下异常：

Failed to process input buffer ( *** -[NSConcreteFileHandle writeData:]: Bad file descriptor )

解决方法

需要更改outputFileHandle行：

outputFileHandle  = [NSFileHandle fileHandleForWritingAtPath: self.outputFilePath];

（编辑：李大同）

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