You can create a smooth scrolling effect for your game or app very easily with the built in behavior 8Direction and ScrollTo.
Step 1:
Create a new sprite. You can use an empty sprite or just make it invisible to hide it.
Step 2:
Add the ScrollTo and 8Direction Behavior to the new camera sprite.
Step 3:
Edit the 8Direction behavior properties. The image shows some suggested values but you should test and change as necessary.
Step 4:
Use the code from the example project to add the scrolling behavior.
Below is the code for the scrolling but there are a few more lines to limit the scrollable area and to stop when the user touches the screen.