Information Technology Reference
In-Depth Information
Figure 15.12 shows the Variables View expanded to full screen size. The view shows a list of objects in the ap-
plication, with disclosure triangles next to each. Clicking a triangle reveals an object's contents, including
named properties. Where relevant, properties may have associated memory addresses or literal values. The cur-
rent object—the one in which the breakpoint was triggered—is labeled
self
.
Standard system objects such as the app delegate, windows, and views have very complex hierarchies. In the
figure, you can see that the app delegate's
window
object includes a long list of properties. Many of the items
in this list are objects in their own right and have further sub-properties that you can explore.
Because the view is unfiltered, it can be difficult to find useful details. As a general rule, you can ignore internal
properties and objects unless you have a good reason to check them. In this example, all the properties of
win-
dow
are irrelevant. But in a more complex project, you might want to check the
_delegate
,
_ini-
tialFirstResponder
or
_frame
properties to see if
window
is being initialized correctly.
TIP
You can also view the contents and structure of an object by hovering the mouse cursor over it. A yellow box ap-
pears with reveal triangles that can drill down through the object hierarchy. This can be a
very
useful debugging
tool.
FIGURE 15.12
Exploring the contents of an object with the Variables View
