How do I append text to a file instead of rewrite?
What would be wrong with reading the file, appending to the string, then resaving the file? Unless you’re dealing with a huge amount of text, the performance will be fine:
NSString * myFilePath = @”/path/to/file.txt”; NSString * myText = [NSString stringWithContentsOfFile:myFilePath];
myText = [myText stringByAppendingString:@”blablabla”];
[myText writeToFile:myFilePath atomically:YES];
The problem is that the text will get really huge (it’s a server log)? Ah.. My bad.
is there a better way?
or should I just make a new log file for every week?
If you are running 10.3, you could look at NSOutputStream. It has initToFileAtPath:append: and write:maxLength: methods. I’ve never used it, but it sounds like it might do what you want.
Open the file as normal with NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:@”path”] Then seek to the end of the file: [handle seekToEndOfFile];
Or you use fopen(“path”, “a”) to get a file descriptor and turn that into an NSFileHandle with [[NSFileHandle alloc] initWithFileDescriptor:fd];
This is exactly what [NSFileHandle fileHandleForUpdatingAtPath:…] is for.
I believe fileHandleForUpdatingAtPath: is if you want to read AND write, rather than for appending vs. overwriting. The open and jump to end mentioned above (fileHandleForWritingAtPath: followed by seekToEndOfFile) seems to be the simplest solution.
Unfortunately, that approach has a race condition if there’s any possibility of other processes modifying the file at the same time. Opening the file in append mode means your data will always go at the end even if somebody else added data to the file between your seek and your write.