When I display the PKToolPicker in my app it looks similar to the image below
If you use one of the apps from Apple like Pages or Freeform you see a picker similar to this one.
Notice that the PKToolPicker from the Apple app has 6 tools not including the ruler. With the tool all the way to the left being the writing tool.
How do you get the picker to display with the writing tool? I have looked over the API and I can see where you can set if the ruler is displayed or not but I can't find anything for the writing tool
