NSFileHandle的用法

//

//  FileInfo.m

//  MemoryManage

//

//  Created by macos on 14-8-10.

//  Copyright (c) 2014年 macos. All rights reserved.

//



#import "FileDemo.h"



@implementation FileDemo

-(id) init

{

    if (self = [super init]) {

        NSFileManager *mgr =[NSFileManager defaultManager];

        NSString *path = [NSHomeDirectory() stringByAppendingString:@"/mac.text"];

        NSLog(@"%@",path);

        NSString *data=@"abcdefghijklmn";

        [mgr createFileAtPath:path contents:[data dataUsingEncoding:NSUTF8StringEncoding] attributes:Nil];

        //NSFileHandle无法创建文件

        NSFileHandle *file = [NSFileHandle fileHandleForUpdatingAtPath:path];

        NSLog(@"%@",[[NSString alloc] initWithData:[file readDataToEndOfFile] encoding:NSUTF8StringEncoding]);

        [file seekToFileOffset:0];

        NSLog(@"length:%lu",[file availableData].length);

        [file seekToEndOfFile];

        NSDateFormatter *datefmt = [[NSDateFormatter alloc] init];

        [datefmt setDateFormat:@" yyyy-MM-dd HH:mm:ss"];

        NSString *ndata=[datefmt stringFromDate:[NSDate date]];

        [file writeData:[ndata dataUsingEncoding:NSUTF8StringEncoding]];

        [file seekToFileOffset:0];

        [self copyFileToPath:file ToPath:[NSHomeDirectory() stringByAppendingString:@"/mac.bak.text"]];

        

        [file closeFile];

    }

    return self;

}



-(BOOL) copyFileToPath:(NSFileHandle *)srcFile ToPath:(NSString *)path

{

    NSFileManager *fm = [NSFileManager defaultManager];

    //创建新的空文件

    NSFileHandle *newFile = [fm createFileAtPath:path contents:[srcFile readDataToEndOfFile ] attributes:nil];

    [newFile closeFile];

    return true;

}



@end