iPhone Open Application Development

Dumping the UI Hierarchy

In the absence of a fully functional debugger for the iPhone, one aid to developers is the _dumpUIHierarchy method provided by the UIApplication class. A UI dump shows the associations of all display UI objects to each other in a parent/child type of hierarchy. For example, a navigation bar may appear like this in the dump:

<dict>
        <key>CGRect</key>
        <data>
        AAAAAAAAoEEAAKBDAABAQg==
        </data>
        <key>Children</key>
        <array>
                <dict>
                        <key>CGRect</key>
                        <data>
                        AAAAAAAAoEEAAAAAAAAAAA==
                        </data>
                        <key>Enabled</key>
                        <false/>
                        <key>ID</key>
                        <string>&lt;UINavigationItemView: 0x22fe60&gt;</string>
                </dict>
                <dict>
                        <key>CGRect</key>
                        <data>
                        AAB3QwAA+EEAAIhCAADwQQ==
                        </data>
                        <key>Enabled</key>
                        <true/>
                        <key>ID</key>
                        <string>BTN Settings</string>
                </dict>
        </array>
        <key>Enabled</key>
        <true/>
        <key>ID</key>
        <string>&lt;UINavigationBar: 0x22f380&gt;</string>
</dict>

To invoke a dump, call the UIApplication class's _dumpUIHierarchy instance method:

[ self _dumpUIHierarchy: nil ];

An XML-formatted file will be written to /tmp/UIDump. All windowed objects are written to the dump in the hierarchy in which they are currently allocated.