Here's a crazy idea:

    newstr = [@"%d %@" format 42, @"blah"];

Implement it as a method that takes a dummy parameter, plus a macro:

    - (NSString *)format:(int)dummy, ...
    #define format format:0,

Awful way to do it, but the resulting syntax is not entirely terrible.

I'm not super comfortable with breaking message syntax like that. Also, very wary of using a #define with a short oft used keyword in a library that will be imported in majority of headers.

Exactly I just want this:

  NSString *newS = @"blah " + @(42) + @"!";