A lot of my choices for app reviews are based on first impressions. The app name, description, or image on iTunes will catch my eye. With Tapeline my first impression was, “Is that even possible?” So far as I can tell the answer is “No.”
Tapeline’s promises are pretty incredible, according to the developer you can use your iPhone/iPod Touch to measure any object. In my numerous tests I only came close to an accurate measurement once, with an object approximately 6 inches long. Objects longer than a foot in length I never even came close to an accurate measurement on. I varied my methods, I calibrated my iPhone, then I recalibrated, I re-recalibrated, I re-re-recalibrated (and so on), and yet nothing I did seemed to work.
All my attempts at measuring objects were such utter failures that I will concede the possibility that I may somehow be doing it all wrong. If that is the case, then the developer needs to seriously beef up the instructions so that user error is less of a problem. Instructions are on YouTube, there are none to be found in the app itself.
As near as I can guess, Tapeline uses the accelerometer to gauge distance. If it is possible at all for this app to work, I imagine that it needs much more thorough directions and probably a better calibration process. Although I fear that the developer may have overreached in trying to do something that the iPhone just can’t do.