I am trying to use the startRelativeAltitudeUpdates method on CMAltimeter and don't know how to use the value returned by the relativeAtitude property of the CMAltitudeData object.
The CMAltitudeData documentation says that it is the change since the last reported event, but the header files say that it is the change since the first update. There is no sample code that shows it in action and the examples I can find on the web seem to vary in terms of how to interpret it. I have tested both and neither seem to work in the real world. The former produces cummulative altitude values that are too large, and the latter produces ones which are too small.
I assume I am doing something wrong, but it's difficult to work out what when I am unsure of how to use the API.
Any ideas? Thanks.