problem with NSString's stringByReplacingOccurrencesOfString

[Sebastian Reitenbach]

Hi,

I try to replace "'" with "\'", and also "\\" with "\\\\" using NSString's 
stringByReplacingOccurrencesOfString.

When I for example do this:
escapedFileName = [@"this is a string blah" 
stringByReplacingOccurrencesOfString:@"blah" withString:@"blubb"];
NSLog(@"escapedFileName: %@", escapedFileName);

Then it prints out:
escapedFileName: this is a string blubb

So far, so good.

but when I then try to:
escapedFileName = [@"this is a string' blah" 
stringByReplacingOccurrencesOfString:@"'" withString:@"\'"];
then the NSLog prints out:
escapedFileName: this is a string' blah

also when I try:
escapedFileName = [@"this is a string' blah" 
stringByReplacingOccurrencesOfString:@"'" withString:@"XXX"];
its still printing:
escapedFileName: this is a string' blah

also I have a problem when I try to escape \ characters:
escapedFileName = [@"this is a string\ blah" 
stringByReplacingOccurrencesOfString:@"blah" withString:@"blubb"];
prints:
escapedFileName: this is a string blubb
which replaced blah with blubb, but the backslash is also gone.

therefore, this doesn't work either:
escapedFileName = [@"this is a string\ blah" 
stringByReplacingOccurrencesOfString:@"\\" withString:@"\\\\"];
just strips the backslash, instead of replacing it. NSLog prints:
escapedFileName: this is a string blah

I'm now wondering what the heck I'm doing wrong here?
Any hit with a cluestick is appreciated.
Its gnustep-base 1.24.0 I am using.

cheers,
Sebastian