【Demo 0024】FoundationKit 文件操作

一、NSFileHandle 介绍

     NSFileHandle 类提供文件IO操作的类, 打开文件，关闭文件，读写文件，文件指针重定位等;

二、文件操作常用方法

     1. 打开文件 

      fileHandleForReadingAtPath

      fileHandleForWritingAtPath

      fileHandleForUpdatingAtPath

      2.  读写文件

      readDataToEndOfFile

      readDataOfLength

      writeData

      3. 文件指针定位 

      offsetInFile

      seekToFileOffset

      seekToEndOfFile

      truncateFileAtOffset

      4. 关闭文件

      closeFile 

三、练习代码

    @autoreleasepool {

        NSString* fileName  = NSTemporaryDirectory();

        NSString* txtPath  = [[fileName stringByAppendingPathComponent:@"testfile"]stringByAppendingPathExtension:@"txt"];

        NSString* newPath   = [[fileName stringByAppendingPathComponent:@"newfile"]stringByAppendingPathExtension:@"txt"];

        NSURL* url = [NSURLURLWithString:@"http://www.baidu.com"];

        

        // create source file

        NSData* data = [NSData dataWithContentsOfURL:url];

        NSFileManager* fm = [NSFileManagerdefaultManager];

        [fm createFileAtPath:txtPath contents:data attributes:nil];

        [fm createFileAtPath:newPath contents:nilattributes:nil];

        NSLog(@"data save to %@", txtPath);

        

        

        NSFileHandle* fileReading = [NSFileHandle fileHandleForReadingAtPath: txtPath];

        NSFileHandle* fileWriting = [NSFileHandle fileHandleForUpdatingAtPath: newPath];

        if (![fm isReadableFileAtPath:txtPath])

        {

            NSLog(@"file is not readable");

            return 0;

        }

      

        if (![fm isWritableFileAtPath:newPath])

        {

            NSLog(@"file is not writabel");

            return 0;

        }

        

        NSData* tmpData = [fileReading readDataToEndOfFile];

        [fileWriting writeData:tmpData];

        NSLog(@"%@ file lenght: %lu", newPath, [tmpData length]);

        [fileWriting writeData:tmpData];

        [fileWriting seekToFileOffset:10];

        NSString* info = @"2013.3.6 ztercel";

        NSData* data2 = [NSData dataWithBytes: [info UTF8String] length:[info length]];

        [fileWriting writeData:data2];

    

        [fileReading closeFile];

        [fileWriting closeFile];

        

        [fm removeItemAtPath:txtPath error:nil];

        [fm removeItemAtPath:newPath error:nil];

        NSLog(@"handle successfully");

    }

 

 

演示实例