What are these called in Objective C? @"%@" @"%d" @"%i"
They are called format specifiers, could also be called 'placeholders in a string for the variables that will follow'.
They are NSString literals. More specifically, they look they are being used as formatting strings for printf style functions.
I believe that they are called 'format placeholders', as suggested by this wikipedia article: http://en.wikipedia.org/wiki/Printf_format_string#Format_placeholders
来源：https://stackoverflow.com/questions/7906948/name-for-d-in-an-nsstring