Touch ID used to unlock your iPhone by scanning your finger (or thumb) prints. The Touch ID sensor sits in the home button of the iPhone 5s and iPhone 6 (and soon the new iPad if rumours are to be believed). With Touch ID set up you can unlock your iPhone just by placing a finger or thumb against the home button of Apple device.

You can also make purchases from the App Store without entering your App Store passcode, just tap your finger against the Home Button. Touch ID was always a cool feature, but it’s recently become far more useful thanks to iOS 8. In the latest version of Apple’s iPhone operating system developers can integrate Touch ID into their apps: using the Touch ID feature to allow access to an app, and its contents. This is a godsend for apps that contain sensitive information, such as your banking details or personal data. Using Touch ID enables you to boost the security across your iPhone, and still quickly access different apps.

In this feature we’re going to look at how to set up Touch ID, and how to use it to unlock the iPhone and using Touch ID with new apps.

Updated: 20 May 2016, to include Apple's new passcode requirement.

See also:

How to set up the best privacy settings in iOS 8

The best iOS 8 widgets & extensions

Using extensions in iOS 8

Best apps that use Touch ID

How to set up Touch ID on an iPhone accurately

Setting up Touch ID on an iPhone couldn’t be easier. It’s typically set up for one finger or thumb during the initial start up process. If you own an iPhone 5s or iPhone 6 the iPhone will ask to scan one finger if you say yes to setting up a Passcode.

If you said no to setting up a Passcode (many people find entering the four-digit code annoying) then we suggest you quickly change your mind and set up Touch ID in the settings. Follow these instructions to set up Touch ID:

  1. Tap Settings > Touch ID & Passcode and Turn Passcode On.
  2. Enter and Reenter a four-digit code. Make sure it’s something you can remember, but not something another person will guess (such as your birthday).
  3. Set iPhone Unlock to On. A Touch ID screen will appear.
  4. Place the thumb or finger that you use most frequently against the Home Button. Do not depress the Home Button: rest the finger against the Home Button with pushing it.
  5. Place Your Finger. The iPhone will buzz and a new screen appears called Place Your Finger. Now repeatedly lift and place the middle of the finger or thumb on the Home Button. You may be asked to slightly move your finger or thumb (but generally aim for the middle of your fingerprint) Each time you tap your finger to the phone the thumb graphic in the middle of the screen fills up in red (signifying that the thumb is being scanned).
  6. Adjust Your Grip. When you have scanned your eight times a new window appears called Adjust Your Grip. The next window is called Adjust Your Grip and is used to scan the edge of the thumb, or finger. This helps improve the accuracy of the Touch ID sensor. Tap Continue.
  7. Now tap the inside of your finger or thumb that normally rests against the Touch ID sensor. If tapping your thumb on your right hand, for example, tap the inside left part of the thumb. If tapping a finger tap the forward part (just underneath the nail). Tap this same spot repeatedly until Touch ID has scanned it.

That’s how to set up Touch ID accurately. Touch ID is also activated for iTunes & App Store, but you can deselect this option in the Touch ID & Passcode settings. We find it handy to be able to download apps without having to enter the Apple Store password each time.

Add five fingers to Touch ID

Once you have set up Touch ID it is best to add multiple fingers. This enables you to access Touch ID using different hands, and when holding or tapping the phone on a surface. You can add up to five fingers using Touch ID, we usually add both thumbs and the index and middle finger on our dominant hand, and index finger on our non-dominant hand.

Here’s how to add more fingers to Touch ID:

  1. Tap Settings > Touch ID & Passcode and Add a Fingerprint
  2. Place your finger repeatedly on the Touch ID sensor.
  3. Place the edge of your finger repeatedly on the Touch ID sensor.

Now repeat this process for up to five of your fingers.

How to use Touch ID in apps

Touch ID now works with a range of different apps. You do not scan your finger into the apps again, instead they access the Touch ID system which authorises your finger. There are a few apps that support Touch ID, and most of them do so to enable you to access the app (and its data). Many apps also request a four digit unlock code, which can be different to the main unlock code on your iPhone.

This provides a second layer of support, with your iPhone requiring finger access to unlock and then the app requesting further authorisation to work.

Passcode requirements

On 18 May 2016 Apple secretly released an update for Touch ID, meaning you'll need to enter your passcode if your iPhone hasn't been unlocked for six days or if it hasn't been unlocked through Touch ID in the last eight hours.

You will still need a passcode, if your iPhone has been restarted, not unlocked for the last 48 hours, been locked by the Find My iPhone program, had a new fingerprint added or have had five unsuccessful Touch ID attempts.

This new update means a passcode will have to be used more often. This is done for your security, whilst others believe it's because of Apple's stance on privacy versus the US government, whereby a passcode protects your rights of sharing information, and biometric access doesn't protect you from incrimination.

Can developers scan my fingerprint?

No. Your fingerprint is stored at all times in a separate part of the iPhone processor, known as the Secure Enclave. Apple can’t get at your fingerprint, third-party developers cannot get at your fingerprint and as far as we know no hackers have managed to extract a fingerprint from the Secure Enclave (theoretically they shouldn’t be able to ever get at your fingerprint). According to Apple – even they cannot get past your passcode (even if the US government hands them a warrant). Your fingerprint is secure.