Graphics Programs Reference
In-Depth Information
To create an intermediate file, the preprocessor resolves all the preprocessor directives in
the implementation file. Preprocessor directives are statements prefixed with the pound
symbol (#), like
#import
. The resolution of a
#import
statement replaces the import
statement with the contents of the imported file. (You can view the contents of an impor-
ted file by Command-clicking the import statement.)
For example, consider
WhereamiViewController.m
, which imports
Wheream-
iViewController.h
. The intermediate file created for
WhereamiViewControl-
ler.m
contains all the code from
WhereamiViewController.h
and
Wheream-
iViewController.m
. But, it doesn't stop there.
WhereamiViewController.h
imports two files,
UIKit.h
and
CoreLocation.h
. These two files import more head-
er files, which import more header files, and so on. The intermediate file for
Wheream-
iViewController.m
is all of the code in all of these files (
Figure 4.16
).
Figure 4.16 Preprocessor creates intermediate files
