Timelines & Triggers - Learn SpriteBuilder for iOS Game Development - page 152

Timeline. Then rename this node to triggers . This will be the container for all the trigger
nodes.
Now you can drag a TriggerOnce from the Tileless Editor View onto the
triggers node in the Timeline. Change the trigger's Name property on the Item
Properties tab to triggerSawRotation . The name connects the trigger with nodes of
the same name—the saw nodes you've added earlier also have triggerSawRotation as
their name. The target nodes will receive a message when the player (or other nodes)
cause the trigger to activate.
Change the trigger's position, and use the selection handles to resize (scale) the object to
best match the desired size of the trigger area. Just make sure the player will be able to
collide with it.
You can also create copies of this new trigger if you want to form a more complex trigger
shape. Multiple triggers can overlap without issues.
Creating the Trigger Class
If you were to build and run the Xcode project now, you would receive an error originat-
ing from CCBReader that states that the custom class Trigger cannot be found. You
may want to try and run the project just to get acquainted with the error message, as you'll
probably encounter it from time to time.
To fix this error, you'll need to add a class of the same name as you've entered under the
Item Code Connections tab in the Custom class field of the trigger's color
node. That class' name is Trigger , in case this wasn't obvious.
In Xcode, select the Project Navigator tab. That's the leftmost tab where the files,
groups (yellow folder icons), and folders (blue folder icons) are shown in a hierarchical
view not unlike Finder displays files and folders. Right-click the Source group and se-
lect New File . This will open the same dialog as in Figure 2-9 . From the iOS Cocoa
Touch section, select Objective-C class, and then click Next , which will show the dialog
you see in Figure 2-10 . Enter Trigger in the Class field, and make it a Subclass of
CCNode before clicking Next . You'll end up with two new files in the Xcode project,
named Trigger.h and Trigger.m .
Again, try to run the project, and once more you'll receive an error message regarding a
missing property named triggerCount . The Trigger class is still missing this prop-
erty or ivar.