Figure 9-25 Analyze getTimelineDataItemOfIndex:
So the caller of getTimelineDataItemOfIndex: can be obtained by [[MMServiceCenter
defaultCenter] getService:[WCFacade class]]. Next, let’s continue with calcDataItemIndex:.
From the instruction “MOV R0, R4”, we know the caller is R4 and R4 is “self”. The argument is
from the return value of [indexPath section], as shown in figure 9-26 and 9-27.