This is the designated initializer syntax of C99, it has nothing to do with Objective C or dictionaries. You use this syntax to initialize "plain" C structures in contexts where calling CGRectMake
is not possible - for example, when you initialize a static variable.
Note that in your case you could have used CGRectMake
as well for a shorter, easier to read, code:
CGContextDrawImage(bmContext, CGRectMake(0.0f, 0.0f, _fullWidth, height), partialImg);