Source code linebreak in NSString constant

[SteveMobs]

I hope it's not an obvious/dump question but I just don't know how to search for it in this forum or the web.

In my implementation file I have a rather long NSString constant. To improve readability I would like to break this constant into several lines.

So I am not looking for a linebreak in the displayed string, rather a way to break a string over several lines in the source code.

Here is an example in Java code. Is there something like a '+'-Operator for NSString as well?

String s = "this"
    + " is a"
    + " very long"
    + " string";

Thanks!

[SteveMobs]

Oh, I'm sorry. Think I just found a solution myself by expermenting.

This seems to work:

NSString *s = @"this" \
    @" is a" \
    @" very long" \
    @" string!";

Can someone please confirm that this is the best way to do a linebreak?

[smasher]

These are all valid ways to split a string across multiple lines:

	NSString *s = @"this" \
		@" is a" \
		@" very long" \
		@" string!";
	
	NSLog(s);
	
	
	NSString *s1 = @"this" 
		@" is a" 
		@" very long" 
		@" string!";
	
	NSLog(s1);
	
	NSString *s2 = @"this"
		" is a"
		" very long"
		" string!";
	
	NSLog(s2);
	
	NSString *s3 = @"this\
 is a\
 very long\
 string!";
	
	NSLog(s3);

The last one is probably the worst; it's hardest to understand what's in the string and what isn't, and it will break your indenting.

I prefer this one:

	NSString *s2 = @"this"
		" is a"
		" very long"
		" string!";

It's short and sweet. They all do the same thing, though.

[SteveMobs]

Thanks a lot!

.. I just wonder where to find out about things like that, is it covered by any documentation?

[smasher]

Originally Posted by SteveMobs

Thanks a lot!

.. I just wonder where to find out about things like that, is it covered by any documentation?

Sort of. The one you found is mentioned here:

Mac Dev Center: The Objective-C Programming Language: Language Summary

The one I like is a side effect of C strings; if you put a bunch of C string constants in a row with only whitespace separating them you get a single C string, which gets processed by the @ directive.

The backslash stuff comes from C, which lets you continue any line by ending it with a backslash:

"A continued line is a line which ends with a backslash, \. The backslash is removed and the following line is joined with the current one. No space is inserted, so you may split a line anywhere, even in the middle of a word. (It is generally more readable to split lines only at white space.)"

Unfortunately there's a lot of C stuff that isn't covered in iPhone or Objective-C books, so it pays to keep a copy of K&R handy.

Lurkers should note that *none* of these methods work if you're not dealing with constants. Every one of them works at compile time, not while the program is running.