如何以附加模式写入文本文件

Question

我的应用程序基于导航。 UItextView 用于注释 UIViewController。我正在将文本数据写入文件。现在我需要在附加模式下编写，我正在尝试以下代码，但每次都使用相同的文本数据写入两次，并且不附加下一个文本数据到文件。

- (void)saveText:(id)sender
{
    [self.textview resignFirstResponder];
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [documentPaths objectAtIndex:0];
    NSString *documentTXTPath = [documentsDirectory stringByAppendingPathComponent:@"Notes.txt"];
    NSString *savedString = textview.text;
    [savedString writeToFile:documentTXTPath atomically:YES];


    NSFileHandle *myHandle = [NSFileHandle fileHandleForUpdatingAtPath:documentTXTPath ];
    [myHandle seekToEndOfFile];
    [myHandle writeData:  [savedString dataUsingEncoding:NSUTF8StringEncoding]];
    [myHandle closeFile];

}

Answer 1

删除下面这行代码

[savedString writeToFile:documentTXTPath atomically:YES];

，剩下的代码就都没有问题了。无论如何也检查我的代码，

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *documentTXTPath = [documentsDirectory stringByAppendingPathComponent:@"Notes.txt"];
    NSString *savedString = textview.text;
    NSFileHandle *myHandle = [NSFileHandle fileHandleForWritingAtPath:documentTXTPath];
    [myHandle seekToEndOfFile];
    [myHandle writeData:[savedString dataUsingEncoding:NSUTF8StringEncoding]];

Answer 2

尝试一下它效果很好

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *documentTXTPath = [documentsDirectory stringByAppendingPathComponent:@"Notes.txt"];
NSString *savedString = textview.text;

如果文件不存在创建它并写入文件，否则它已经创建附加到文件末尾

NSFileManager *fileManager = [NSFileManager defaultManager];
if(![fileManager fileExistsAtPath:documentTXTPath])
{
  [savedString writeToFile:documentTXTPath atomically:YES];
}
else
{
  NSFileHandle *myHandle = [NSFileHandle fileHandleForWritingAtPath:documentTXTPath];
  [myHandle seekToEndOfFile];
  [myHandle writeData:[savedString dataUsingEncoding:NSUTF8StringEncoding]];
}

Answer 3

您还可以

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *documentTXTPath = [documentsDirectory stringByAppendingPathComponent:@"Notes.text"];
NSString *content = [NSString stringWithContentsOfFile:documentTXTPath encoding:NSUTF8StringEncoding error:nil];
content = [content stringByAppendingString:data];

再次将内容写入特定文件路径

[content writeToFile:documentTXTPath atomically:YES encoding:NSUTF8StringEncoding error:nil];