For detecting iMessages, there should be a conversion from dataSource to placeholder, and this
conversion process is the actual meaning of “detecting iMessages” as well our target in this
section, as shown in figure 10-2.
Figure 10- 2 Conversion from dataSource to placeholder
You may wonder, since figure 10-2 is so straightforward and dataSource is already known,
why don’t we start from it directly and trace placeholder? Then we can reproduce the process
and achieve our goal. Actually, we’re not living in a fairy tale, the real world is usually not
idealized. For one thing, we don’t have the source code of MobileSMS; for the other thing, in
general cases, the conversion is much more complex, as can be illustrated in figure 10-3.