Question

I want to self assign an adjusted nsstring via category.
The example is a trim function:

I do not want that way:

NSString *theTempString = [theExampleString xTrim];
// ... go on doing stuff with theTempString

I want it this way:

[theExampleString xTrim];
// ... go on doing stuff with theExmapleString

The category looks like this:

- (void)xTrim
{
    self = [self stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceCharacterSet]];

}

The error that an assignment outside init is not possible – I understand that.
But now I’m interested in it, of course I can write an custom init methode, but is there no way around it like the one above???

Greetings and thanks,

matthias

Answer 1

You don’t need to create a new NSString, the method already does that for you:

- (NSString *)xTrim
{
    return [self stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
}

NSString is immutable so you need to assign it:

yourString = [yourString xTrim];