Edit object with vertices tools

To add vertex

1. Select "Insert vertex" tool 
2. Tap on object to select it 
3. Tap anywhere on the object to add vertex

To remove vertex

1. Select "Remove vertex" tool 
2. Tap on object to select it 
3. Tap on vertex you wish to remove

Edit object 

1. Select "Edit vertex" tool 
2. Tap on object you wish to edit
3. Drag vertex to desired location

To activate halo for precise control, tap on the vertex. You can now drag a halo without covering vertex with you finger.

Watch video tutorial