stop files from truncating objective C? - iphone

Question

I am trying to write some data to a file in iphone sdk....I am using a for statement to write to explain the situation better I have some code:
for(int i = 0;i < 11;i++){
NSString *myFile = [documentsDirectory stringByAppendingPathComponent:#"hello.txt"];
[i writeToFile: myFile atomically:NO encoding:NSUTF8StringEncoding error:NULL];
}
now I expect 12345678910 to written in the file but only 10 is written in it which means file is being trncated everytime I write to file..so my question is what can I do to write 1 to 10 WITHOUT puttting everything in a string because I have alot of data..
thanks

Answer 1

The SDK documentation says this about -writeToFile:atomically:encoding:error: This method overwrites any existing file at path.
That method is intended for dumping a string out to a file. For your purposes, you can either build up a string, or open a file with [NSFileHandle fileHandleForWritingAtPath]:
NSString *myFile = [documentsDirectory stringByAppendingPathComponent:#"hello.txt"];
NSFileHandle *file = [NSFileHandle fileHandleForWritingAtPath:myFile];
for(int i = 0; i <= 10; i++) {
NSString *dataString = [NSString stringWithFormat:#"%i", i];
[file writeData:[dataString dataUsingEncoding:NSUTF8StringEncoding]];
}
[file closeFile];

Answer 2

If you're trying to write a series of integers to a file, I would go about it like this:
NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:FILE_PATH];
for(int i=0; i<11; i++)
{
NSString *str = [NSString stringWithFormat:#"%d",i];
[fileHandle writeData:[str dataUsingEncoding:NSUTF8StringEncoding]];
}
[fileHandle closeFile];