IOS文件的简单读写实例详解

ios文件的简单读写实例详解

数组(可变与不可变)和字典(可变与不可变)中元素对象的类型,必须是nsstring,nsarray,nsdictionary,nsdata,否则不能直接写入文件

 #pragma mark---nsstring的写入与读取---
  //1:获取路径
  nsstring *docunments = [nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes)firstobject];
  //2:在该路径下创建文件夹,文件夹名为字符串.txt
  docunments = [docunments stringbyappendingstring:@"/字符串.txt"];
  //  nslog(@"%@",docunments);
  //3:编写文本内容
  nsstring *str = @"大家一起来";
  //4:将文本写入到"字符串.txt"中
  /*
   writetofile:文件路径,在这里是documents atomically:yes(若为yes,则保证了文件的原子性,即先创建一个临时文件,直到文件内容写入成功再导入目标文件(字符串.txt),为no,直接写入目标文件里) encoding:编码格式是个枚举值 error:错误信息,一般为nil

   */
  bool result = [str writetofile:docunments atomically:yes encoding:nsutf8stringencoding error:nil];
  if (result) {
    nslog(@"我成功了");
  }else{
    nslog(@"为啥失败了");
  }

  //读取
  /*
   stringwithcontentsoffile:路径 encoding:编码 error:nil,错误信息

   */
  nsstring *newstr = [nsstring stringwithcontentsoffile:docunments encoding:4 error:nil];
  nslog(@">>>>%@",newstr);
  /*
   .plist全名是：property list，属性列表文件，它是一种用来存储串行化(当程序彻底退出后,对象就会随之消亡,但是,我们希望有些东西需要记录下来,以便于恢复,也可提升用户体验,而记录的这个过程,就叫串行化)后的对象的文件。属性列表文件的扩展名为.plist ，因此通常被称为 plist文件。文件是xml格式的。
   注意:plist文件通常用于存储用户设置,也可用于存储捆绑信息
   */
#pragma mark---nsarray的写入与读取


//获取路径
  nsstring *arraydoc = [sandbox getdocuments];
  //在arraydoc下拼接文件名
  nsstring *arrpath = [arraydoc stringbyappendingstring:@"array.plist"];
  //向数组中写入数据
  nsarray *array = @[@"25",@"55",@"05",@"5885"];
  //将数组写入文件
  [array writetofile:arrpath atomically:yes];
  nslog(@"数组存入路径%@",arrpath);

  //读取
  nsarray *newarray = [nsarray arraywithcontentsoffile:arrpath];
  nslog(@"读取的文件:%@",newarray);
#pragma mark--- 字典的写入与读取----
  nsstring *dicionarydic = [sandbox getdocuments];
  nsstring *dicpath = [dicionarydic stringbyappendingstring:@"dictionary.plist"];
  nsdictionary *dictionary = @{@"name":@"甲甲",@"age":@"18"};
  [dictionary writetofile:dicpath atomically:yes];
  nslog(@"字典存入路径%@",dicpath);

  //读取
  nsdictionary *newdict = [nsdictionary dictionarywithcontentsoffile:dicpath];
  nslog( @"读取的字典文件%@",newdict);

#pragma mark--- nsdata----
  nsstring *datapath = [[sandbox getdocuments]stringbyappendingstring:@"data.data"];
// nsstring *string = @"丑八怪";
//  nsdata *data = [string datausingencoding:nsutf8stringencoding];

  uiimage *image = [uiimage imagenamed:@"2"];
  nsdata *data = uiimagejpegrepresentation(image, 0.5);

  [data writetofile:datapath atomically:yes];
  nslog(@"%@",datapath);
  //读取
  nsdata *newdata = [nsdata datawithcontentsoffile:datapath];
//  nsstring *new = [[nsstring alloc]initwithdata:newdata encoding:4];
  uiimage *new = [uiimage imagewithdata:newdata scale:1];

  nslog(@"%@",newdata);
  nslog(@"%@",new);
}

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