How Can I Tell If I Have A Secret App On An Iphone 6s

This story has been updated. It was originally published on May 15, 2017.

Both iPhones and Android devices have their pros and cons, but the general consensus is that iOS is a little easier to pick up and use, while Android offers more in the way of customization and configuration. Still, simple as Apple's operating system seems, you can find plenty of advanced features hidden below its polished surface.

If you don't know these handy iPhone tricks exist, however, you might never discover that you can hide private photos, use your phone as a level, activate a hidden trackpad, teach Siri nicknames, and more. We're here to show you the way.

Use the keyboard as a trackpad

Did you know the iPhone keyboard can double as a trackpad? With this feature, you'll be able to move the cursor more accurately and jump to bits of text, all without having to tap on the screen. To use it, you'll need an iPhone with 3D Touch capabilities (iPhone 6S or newer), and this trick also works on any iPad.

On the iPhone, firmly press and hold anywhere on the keyboard to activate the trackpad. Once the keyboard goes blank, you're in business. Then, drag your finger around to move the cursor through the text. On an iPad, drag two fingers in any direction on the keyboard to activate trackpad mode.

Check that a surface is level

The iOS leveling tool on the iPhone, showing an angle difference of seven degrees. — The built-in leveling tool is one of several iPhone features that will help you out around the house. *David Nield*

You might not have realized that the built-in iOS measurement app has leveling capabilities. Even if you did, you might not not have picked up on some of the things it can do. To find it, open Measure and tap Level on the right.

You can use the level with your phone laid flat or perched on its side in either portrait or landscape mode. If you want to measure the difference between two surfaces or are dealing with a set surface that's not perfectly horizontal or vertical, tap the screen to set the angle to zero. Then move your phone—the red area will show you how much the two angles vary.

Use it to make sure your pictures are hanging correctly and your DIY is up to scratch. An iPhone may not be as precise as a dedicated bubble level, but it's still handy.

[Related: How to print and frame a photo that deserves more than Instagram]

Hit backspace in Calculator

If you spend a lot of time inside the iOS Calculator app, you know the frustration of mistyping a digit and having to start the calculation all over again. This hidden backspace function means you won't have to hit the C or AC buttons every time you make a mistake. Just swipe to the left or right at the top of the screen where the digits are displayed. The motion acts as a backspace command, and will remove the number you entered last.

While we're talking about Calculator, have you ever put the app into landscape mode with a twist of your iPhone? This view reveals a host of extra functions, but it will only work if your phone's orientation isn't locked in portrait mode. To check, open your phone's Control Center by swiping down from the upper right corner of the screen on an iPhone X or later, or up from the bottom of the screen on the iPhone SE and other devices. Find the lock with an arrow around it and make sure it's not activated.

Hide your private photos

An iOS option to hide a photo of jalapeño poppers from being visible to anyone viewing your camera roll. — Yes, I'm hiding this photo of jalapeño poppers because they look too good. No, you can't see them. *John Kennedy*

We all hand our phones over to friends when we want to share photos or videos. But what if your collection includes sensitive images you'd rather not show anyone else? Luckily, the iPhone makes it easy to hide your most personal pictures from view.

Inside Photos, select one or more images, then tap the Share button and choose Hide. As the confirmation message says, your chosen pictures will disappear from every location in your library, but you'll still be able to see them in the Hidden folder within your Albums.

Go to bed on time

In addition to letting you set alarms so you'll wake up on time, iOS will help you stick to a given bedtime. Open up the Health app on your iPhone, click Browse in the bottom right, find Sleep, and go to the Your Schedule section. If you haven't set a sleep goal, the app will ask you to do so. If you have, tap Full Schedule & Options to change it.

Now it's time to set a sleep schedule. Tap Add under Your Schedule or Set Your First Full Schedule under Full Schedule and choose which days you want the sleep plan to be active. Then, slide the bedtime and wake up sliders around the clock graphic to set times for each (the slider will turn orange if you've chosen times that don't meet your sleep goal). Next, set your alarm options. Your iPhone will ping you when it's time to hit the hay, automatically turn on Do Not Disturb, and track how well you're doing at reaching your sleep targets.

Get your lost phone back

The iPhone Medical ID option, with an activated toggle switch to show emergency information on the lock screen. — Your medical ID can give first responders key information about you, but it can also help you get your phone back. It's one of the few iPhone tips that can save your life. *David Nield*

Even if you don't use the Apple Health app, it's worth filling out the Medical ID section. That's because the details you enter here, such as your allergies and contact information for your next of kin, will appear on the lock screen when someone taps the dialer's Emergency link. In other words, anyone who picks up your device can access this information. So, if you lose your phone, a helpful bystander can tap through to find a way to return it.

[Related: Smartphone settings that could save your life]

To find your Medical ID, enter the Settings app, find Health, tap Medical ID, and hit Edit. Then plug in whatever information you'd like. If you want to make sure people can it, toggle the Show When Locked switch to "on."

Another, better-known way to locate a lost device is the Find My iPhone feature, which lets you track your phone on a map. Activate the ability in the Settings app by tapping your name and selecting Find My.

Receive notifications via camera flash

Those of you who prefer a visual phone alert to an audible one will like this relatively secret setting: You can get your camera's flash to blink several times whenever you receive a notification.

To get the feature working, go into Settings and tap Accessibility. Then, enter Audio/Visual and switch the LED Flash for Alerts toggle switch to "on." If you'd prefer to not be disturbed at all when the phone is in silent mode, you can tell the flash not to light up then. This is one iPhone camera trick that has nothing to do with photos—just make sure no one thinks you're snapping a shot of them when you're out and about.

Teach Siri to use nicknames

An iPhone contact card with the contact's nickname set to "mom." — Nicknames will help you differentiate all the Davids and Johns in your contacts. *David Nield*

Siri is pretty adept at working out who you want to text or call. But you can speed up the process by adding nicknames like "mom" or "Lizzie" to your contacts. In fact, Apple's Contacts app has a field especially for this, and Siri can use it to identify people.

To manually input a nickname, open any contact card, tap Edit, choose Add field, and select Nickname from the list. Siri will also remember your relationships. Tell the assistant to "call mom" or "call my boss," and it'll ask which contact that designation belongs to and whether it should remember for future calls. If you want to manually assign a relationship, tap on your own contact card, hit Edit, and then add related name. Choose from a number of different relationships and tap the "i" icon to link that relationship to a specific contact.

Magnify what the camera sees

The ability to zoom in on real-world images might prove helpful in all kinds of situations, such as when you're squinting at a menu in a dimly-lit restaurant. To use it, go to Settings, open Accessibility, and then tap Magnifier to toggle the feature on.

With Magnifier on, you can launch the iOS Camera app and triple-tap the side button (the Home button on older phones) to bring up the Magnifier option. Use the slider at the bottom of the screen to take a closer look at anything—even closer than your camera's zoom.

Write on email attachments

A Popular Science image sent as an email attachment that has been marked up with the iOS markup tool — For when you're emailing someone who really needs a big red circle to see the important part of an image or PDF. *David Nield*

Sometimes, an email attachment just doesn't convey enough information on its own. So annotate it with Apple's built-in Mail app. Digital scribbles, text overlays, a zoom-in magnification window, digital signatures—you can add all of these on top of email attachments.

To modify an image or PDF attachment you've received, just open it and tap the markup icon (a pen tip in a circle) in the top right. When you hit Done, it'll ask how you want to reply or if you want to discard your changes. If you choose to reply or create a new message, you'll be able to review your email before you send it. For a file you've attached to a new email, tap the attachment and select Markup.