Here is a look at the iPhone's compass feature and how to use it effectively.
No Direction Home
The iPhone has added new features with each new incarnation, and one of the favorite features that was released along with the iPhone 3Gs is the compass. The iPhone's compass feature works in the same way that you would assume, but it actually feeds into the same features that allow for the iPhone location function. Here are a few tips for working with the iPhone's Compass, which is unique in its implementation.
How Does the iPhone Compass Work?
The iPhone Compass works in the same way as the basic compass design has for hundreds of years. When you open the iPhone's Compass it will calibrate to your location and you will find that there is a visual compass in the center. This will show you a general directional reading of which way North is, and above there will be a numeric reading of your point of view. At the very bottom you will find that the iPhone Compass also works as a reading of your current latitude and longitude, which is listed numerically as coordinates in both measurements.
What is nice about the iPhone's Compass is that you will not need to keep it entirely horizontal as you would with a standard compass to keep the iPhone Compass calibrated. Instead, you can tilt in in a direction so that you have the ability to see the image and the Compass will still find its overall calibration. As long as you reposition your Compass in a few different ways you will be able to trust the reading that comes up. If you are having an issue with the reading you should try to close and open it once to ensure the iPhone Compass has calibrated.
Interference can be a major problem for the iPhone's Compass as electromagnetism will disrupt it. To solve this interference you need to remove your iPhone from the source of that interference, and then rotate it in a figure eight pattern to try and fix the orientation. If it does not fix quickly then you may want to close it out and re-open the Compass application.
Your iPhone's Compass actually allows you to switch between True North and Magnetic North, which is not exactly in line with geographic north. To make the choice between these two orientations of north you should go to the "i" button in the lower right hand corner of the iPhone's Compass. Here you can make the choice between the two, but the default is True North and this will remain more useful for you when trying to use it to navigate.
If you look to the bottom left hand corner of your iPhone's Compass display, adjacent from the "i" you use to choose the north orientation, you will find a small Crosshair button. If you select this button you will be switched over to your iPhone's Maps function. From here it will pinpoint your exact location on that map.
One of the most requested functions of the iPhone's Compass feature is to use it inside Google Maps. This is actually baked right in to Google Maps, if you start out by opening it and selecting the Crosshair button. This will show you your exact location, in the same way that selecting the Crosshair button in Compass did before. If you press the Crosshair button again you will find that your blue dot position in Google Maps will become a triangle, the open part of which indicates the direction you are looking. It will then respond to the direction the iPhone is directed in the same way that the read out in Compass does. As long as the iPhone Compass calibration is correct then you will be able to assess which direction to go right from the moment you identify your location in Google Maps.