What is the typical approach taken for writing NSString objects to a file?

Question

As an example, I want to write out some string value, str, to a file, "yy", as it changes through each iteration of a loop. Below is how I'm currently implementing it:

NSOutputStream *oStream = [[NSOutputStream alloc] initToFileAtPath:@"yy" append:NO];
[oStream open];

while ( ... )
{

    NSString *str = /* has already been set up */

    NSData *strData = [str dataUsingEncoding:NSUTF8StringEncoding];
    [oStream write:r(uint8_t *)[strData bytes] maxLength:[strData length]];

    ...
}

[oStream close];

Ignoring the UTF-8 encoding, which I do require, is this how NSStrings are typically written to a file? That is, by first converting to an NSData object, then using bytes and casting the result to uint8_t for NSOutputStream's write?

Are there alternatives that are used more often?

EDIT: Multiple NSStrings need to be appended to the same file, hence the loop above.

Answer 1

ctshryock's solution is a bit different than yours, since you're appending as you go, and ctshyrock's write a single file all at once (overwriting the previous version). For a long-running process, these are going to be radically different.

If you do want to write as you go, I typically use NSFileHandle here rather than NSOutputStream. It's just a little bit easier to use in my opinion.

NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:aPath];
while ( ... )
{
    NSString *str = /* has already been set up */

    [fileHandle writeData:[str dataUsingEncoding:NSUTF8StringEncoding]];
}

[fileHandle closeFile];

Note that fileHandle will automatically close when it is dealloced, but I like to go ahead and close it explicitly when I'm done with it.

Answer 2

I typically use NSString's methods writeToFile:atomically:encoding:error: or writeToURL:atomically:encoding:error: for writing to file.

See the String Programming Guide for Cocoa for more info