如何在目标C iphone中的文本文件中写入内容 [英] how to write content in text file in objective C iphone

问题描述

我正在iPhone上写内容。我用这个代码

  NSArray * paths = NSSearchPathForDirectoriesInDomains（NSDocumentDirectory，NSUserDomainMask，YES）; 
 NSString * filePath = [[paths objectAtIndex：0] stringByAppendingPathComponent：@data.txt]; 
 NSString * temp = [[NSString alloc] initWithString：@my name is gaurav]; 
 [temp writeToFile：filePath atomically：YES encoding：NSUTF8StringEncoding error：nil]; 
 [临时发行]; 
  

当我试图用这段代码用新内容写这个文件的时候

  NSArray * paths = NSSearchPathForDirectoriesInDomains（NSDocumentDirectory，NSUserDomainMask，YES）; 
 NSString * filePath = [[paths objectAtIndex：0] stringByAppendingPathComponent：@data.txt]; 
 NSString * matter = [[NSString alloc] initWithString：@Hello iPhone]; 
 
 [writeToFile：filePath atomly：YES encoding：NSUTF8StringEncoding error：nil]; 
 [释放事项]; 
  

如果我以原子方式传递YES，那么文件不会被覆盖。如果我放置没有那么文件将覆盖，但程序也停止并退出。

  [matter writeToFile：filePath atomically：YES编码：NSUTF8StringEncoding错误：无]; 
  

解决方案

这是工作。你只是创建测试项目。并在viewDidLod方法中编写下面的代码。并从文档目录中查看文本文件内容。它会被覆盖。

   - （void）viewDidLoad 
 {
 [super viewDidLoad]; 
 //在加载视图之后，通常从笔尖执行任何其他设置。 
 
 NSArray * paths = NSSearchPathForDirectoriesInDomains（NSDocumentDirectory，NSUserDomainMask，YES）; 
 NSString * filePath = [[paths objectAtIndex：0] stringByAppendingPathComponent：@data.txt]; 
 NSString * temp = [[NSString alloc] initWithString：@my name is gaurav]; 
 [temp writeToFile：filePath atomically：YES encoding：NSUTF8StringEncoding error：nil]; 
 [临时发行]; 
 
 NSString * matter = [[NSString alloc] initWithString：@Hello iPhone]; 
 [matter writeToFile：filePath atomically：NO encoding：NSUTF8StringEncoding error：nil]; 
 [释放事项]; 
 
} 
  

I am writing content in iPhone. I used this code

NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
NSString *temp = [[NSString alloc] initWithString:@"my name is gaurav"];
[temp writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[temp release];

While I am trying to over write this file with new content with this code

NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
NSString *matter = [[NSString alloc] initWithString:@"Hello iPhone"];

[matter writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[matter release];

If I passed YES in atomically then file is not overwritten. and If I placed No there then file will overwrite but program is also halted and exit.

[matter writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];

解决方案

I have tried. it is working. you just create test project. and write following code in viewDidLod method. and see text file content from document directory. it will get overwrite.

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
    NSString *temp = [[NSString alloc] initWithString:@"my name is gaurav"];
    [temp writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
    [temp release];

    NSString *matter = [[NSString alloc] initWithString:@"Hello iPhone"];
    [matter writeToFile:filePath atomically:NO encoding:NSUTF8StringEncoding error:nil];
    [matter release];

}

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