I bought an iPhone 6 Plus in early December 2014. I had an iPhone 5 and was really looking forward to ditching the passcode for TouchID, as well as playing media on the way home from work on a bigger screen. My iPhone 6 Plus does have a big, beautiful screen, but I haven’t been able to use TouchID for more than a few hours at a time since I got it.
[Thanks to Gretchen Macdowall for this guest post! -r]
It took me weeks to figure out the problem, which is that the sensor needs sufficient blood flow close to the surface of the skin to work. I have Reynauds Syndrome which impedes blood flow to extremities in the cold. And cold is a very relative thing – sometimes my fingers get numb indoors in my home with the thermostat turned down.
On the day I got the phone, the first thing I did was set up my thumbprint. It worked great for about 2 hours. After that, the recognition reduced to about one in four times and a few hours later the recognition was completely gone. After going through that scenario with the same results for a few days I brought the phone back to the Apple Store and got a replacement. The same thing happened. Less than 24 hours after I got the second phone it would not recognize my finger.
Well, it can’t be the hardware I thought. So I scoured Apple’s Support forum and tried all of the solutions, which are:
- Wipe off the TouchID button with a lint-free cloth
- Don’t use lotion on your fingers
- Don’t touch the phone with wet hands
- Unplug the charging cord
- Reboot the device
- Do a clean restore of the device
- Try registering multiple copies of the same finger
- Try using a different finger
I filed another support ticket and went back to the Apple Store. The technician gave me yet another replacement phone but told me that it was a problem that Apple had “acknowledged” and it would be fixed in the next release which was coming out “soon”. She did not say exactly what the problem was.
I was very excited when 8.1.3 came out and installed it immediately. The recognition was quite a bit better, but it still never made it much past a few hours. I should mention here that I was doing all of my testing at home, where the thermostat is set to 65 degrees in the winter.
In preparation for another Apple Store appointment I brought the phone to work where it is quite warm. I set up a fingerprint in order to document exactly how long it took before recognition would stop. To my surprise, I had perfect recognition for 8 hours. At the end of the day I put on my coat and gloves and walked less than 10 minutes to the car. Inside the car I took off the gloves and tried to wake the phone. No TouchID. And that’s when it dawned on me that the sensor cannot recognize a cold finger with restricted blood flow.
If you have Reynauds and you are considering an iPhone to get TouchID and you live in a cold climate, you should try before you buy. Ask a friend who already has one if you can register your finger. Try out the TouchID over the course of a day in a variety of settings.
If you already have an iPhone and have no recognition, don’t spend a lot of time trying to make the existing prints work. My experience is that once you have a few failed attempts the stored prints will never work again. If you want TouchID, redo them.
I think this problem could probably be fixed with additional software preferences. For instance you should be able to turn off the subdermal part of the TouchID for unlocking the phone. Also, if making the stored prints stop working permanently after a certain number of failed attempts is some kind of intentional security feature, the user should be able to turn it off.
– Gretchen Macdowall