writeToFile未写入文件

Question

嗯，我正在经历一个问题，我已经挣扎了几天了。如下所示:当尝试使用writeToFile写入xml文件(放置在我正在开发的xcode项目中)时，虽然从writeToFile返回的布尔值被计算为true，但是写入不起作用，并且在xml文件中什么也看不到!！此外，文件字节为零。所以，如果有人能帮我解决这个问题，我将不胜感激。下面是我写的代码的一部分：

//writing to a file
 NSString *pathOfFile = [[NSBundle mainBundle] pathForResource:@"sample" ofType:@"xml"];
 NSString *dummyString = @"Hello World!!\n"; 
 NSFileManager *filemanager;

 filemanager = [NSFileManager defaultManager];

  //entering the first condition so I assured that the file do exists
  if ([filemanager fileExistsAtPath:pathOfFile] == YES)
     NSLog (@"File do exist !!!");
   else
     NSLog (@"File not found !!!");


BOOL writingStatus = [dummyString writeToFile:path atomically:YES encoding:NSUnicodeStringEncoding error:nil];

    //Not entering this condition so I am assuming that writing process is successful but when I open the file I can't find the string hello world and file size shows 0 bytes
    if(!writingStatus)
    {
        NSLog(@"Error: Could not write to the file");
    }

我也尝试过这种方法，但不幸的是它也不起作用。

NSString *hello_world = @"Hello World!!\n";
NSArray  *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *directory = [paths objectAtIndex:0];
NSString *fileName = @"sample.xml";
NSString *filePath = [directory stringByAppendingPathComponent:fileName];
NSLog(@"%@",filePath);
BOOL sucess = [hello_world writeToFile:filePath atomically:YES encoding:NSASCIIStringEncoding error:nil];  
if(!sucess)
{
    NSLog(@"Could not to write to the file");
}

Answer 1

在第一段代码中，我们看不到path的定义。如果这是一个拼写错误，并且您指的是file_path，那么问题是file_path指向应用程序包中的路径。你不能在你的应用程序包里写东西。(不应该有任何拼写错误，因为您应该直接粘贴代码。)

在第二种情况下，很难判断问题是什么。filePath应该在可写的documents目录中。然而，如果你得到的是一个实际的错误，那么诊断问题会容易得多。不是为-writeToFile:atomically:encoding:error:中的nil参数传递错误，而是创建一个NSError*变量并传入其地址。如果有问题，那么您的指针将被设置为指向描述问题的NSError对象。

Answer 2

writeToFile:返回布尔值YES这一事实仅仅意味着调用正在完成。

您应该向writeToFile:传递一个NSError**并对其进行检查，例如：

 NSError *error = nil;
 BOOL ok = [hello_world writeToFile:filePath atomically:YES 
                        encoding:NSASCIIStringEncoding error:&error];
 if (error) {
      NSLog(@"Fail: %@", [error localizedDescription]);
 }

这应该会给你一个很好的线索，告诉你哪里出了问题(假设错误在调用后不是零)。

Answer 3

-(void)test{
//writing to a file
    NSError *error;
    NSString *pathOfFile = [[NSBundle mainBundle] pathForResource:@"sample" ofType:@".xml"];//was missing '.'
NSString *dummyString = @"Hello World!!\n";
NSFileManager *filemanager;

filemanager = [NSFileManager defaultManager];

//entering the first condition so I assured that the file do exists
   //the file exists in the bundle where you cannot edit it

    if ([filemanager fileExistsAtPath:pathOfFile]){
        NSLog (@"File do exist IN Bundle MUST be copied to editable location!!!");
        NSArray *locs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *docsDir = [[locs objectAtIndex:0]stringByAppendingString:@"dummyFile"];
        NSString *file = [docsDir stringByAppendingPathComponent:@".xml"];

        [filemanager copyItemAtPath:pathOfFile toPath:file error:&error];
    }
    else{
NSLog (@"File not found in bundle!!!");

    }

    if (error) {
        NSLog(@"error somewhere");
    }


//if youre only messing with strings you might be better off using .plist file idk
BOOL success = [dummyString writeToFile:file atomically:YES encoding:NSUnicodeStringEncoding error:nil];

//Not entering this condition so I am assuming that writing process is successful but when I open the file I can't find the string hello world and file size shows 0 bytes
if(!success)
{
    NSLog(@"Error: Could not write to the file");
}


}