instance variable _composeSendingService. In other words, _composeSendingService is the 6th
data source. In that case, we just need to find where this instance variable is written and there
comes the 7th data sources.
Click _OBJCIVAR$_CKPendingConversation._composeSendingService to focus the
cursor on it. Then press “x” to inspect xrefs to this variable, as shown in figure 10-23.
Figure 10- 23 Inspect cross references
Here, we can find 2 methods explicitly accessing _composeSendingService, which happens
to be one setter and one getter respectively. Naturally, we guess that _composeSendingService
is a property. Open CKPendingConversation.h and verify our assumption, as shown in figure
10-24.
Figure 10- 24 CKPendingConversation.h
In Objective-C, write operation of a property is often carried out through its setter. Thus to
find the 7th data source, we should set a breakpoint on [CKPendingConversation
setComposeSendingService:] and check out who’s the caller. Repeat our previous operations: