So you're on your way back from a restaurant and realize you left your iPhone there, but you're late for a meeting and can't go back yet. You can also kiss this iPhone farewell, right? Not as long as the right person gets their hands on it first. But the potential do-gooder does not know to contact you, and that's where Find My iPhone's "Lost Mode" will be useful.
With the feature lost function in Apple's Find My iPhone, you can remotely place a message on the lock screen with your contact information so that good samaritan will be able to call you to the number you enter. If the business has found it, you will probably get it back without opening your wallet, while some people can expect a seeker's reward of varieties. We leave that part up to you.
Of course, there are cases where a message and contact information is not enough to download your iPhone. If stolen, it is likely that the thief does not care about your grounds for a safe return, and all it will do is to push down the iPhone so that it cannot be tracked, at least until they figure out what to do with it . In that case, you must use Find My iPhone's other tools, but if you think a less sinful person can find it first, Lost Mode works well.
: Log in to find my iPhone
To set this message remotely with lost mode, you need to open Find My iPhone. You can use the iOS app on your iPad or a friend's iPhone, or you can visit the web in a desktop opener on a computer you have access to through iCloud.com. We've found that Find My iPhone's functionality is greatly reduced or not even available from mobile browsers on iOS and Android, so you must stick to a desktop browser if you're not using the iOS app.
Option 1: Using the iOS app
If you have access to another iOS device, this is the easiest way to use the deleted mode. If the app is not already installed on the current device, you can install it yourself from the App Store (it has been a non-removable storage app since IOS 9, so chances are it is already on the device).  When you find the app you open it and if you use someone else's device, you must log out of their Apple ID account if they are already logged in to Search My iPhone. Then just log in with the Apple ID and password attached to your missing iPhone and then proceed to step 2.
Option 2: Using the desktop web
We have tested the web app version in several Android and iOS browsers, and all failed to let We have access to the necessary tools after login (your mileage may vary ), so we stick to the desktop browser and suggest you do the same. If you are using a friend or a regular computer, it is best to use Find My iPhone in a private browser so your data will not be accidentally saved in the browser.
Visit iCloud.com/#find, then log in to your Apple ID account associated with the lost iPhone. Alternatively, you can log in to the main page iCloud.com, then on the two-factor authentication screen, click "Find My iPhone" at the bottom of the page – you don't need full access to iCloud to use Find My iPhone, so don't worry about the verification code.
If you just log in to iCloud.com using the 2FA verification code, you must click on the "Search my iPhone" app from the list of iCloud web application on the Launchpad screen. If you are using a friend or a public computer, make sure you do not press "Don't Trust" immediately after entering the verification code. There is no need to trust.
Step 2: Access to the removal mode for your iPhone
With the map displayed on the screen, you are ready to go. While the process of accessing the deleted location is similar to the iOS app and the web versions of Find My iPhone, there are a few differences that are worth pointing out below.
Option 1: Using the iOS app  Tap the location bubble on the iPhone that is lost, then tap the expanded bubble to access the available tools that you can use remotely on the device. If you cannot find the iPhone in question, tap "All" at the top left and then select iPhone from the list of devices. Then you want to select "Lost Mode", press "Turn on Lost Mode" and proceed to Step 3.
Keep in mind if you know the person who stole or found your iPhone might know your password, you can just be better press "Delete iPhone" next to "Lost Mode". Better to dry your device than to have its data compromised. This is just another example of why it is so important to keep new backups so important.
Option 2: Using the Desktop Web
Click the location bubble on the iPhone that is lost, then click on the info (i) button in the white box that pops up, showing you all the tools available to use remotely. If you can't find iPhone on the map, click "All devices" up and then select iPhone from the list of devices. Then select "Lost Mode" from the list and proceed to Step 3.
Step 3: Add a contact number (Optional)  After you turn on lost mode, in both the iOS app and the web app, you are asked to enter the phone number you want the person to call you.
The phone number should be something you or someone else can answer directly, and you can change the phone number later if you move places. Anyone who finds your iPhone will be able to see the phone number, so make sure it's something you share okay.
If you do not care about entering a phone number, you can also leave this field blank – it is not necessary. When finished, press or click "Next".
Then you will be prompted to enter a message coming to appear on the missing iPhone lock screen along with your contact number if you have added one. You do not need to include a message, but it is a good idea to do so if you want to help someone return your iPhone to you.
What you write should depend on the circumstances. If you have no idea your iPhone is, "This iPhone has been lost. Please call me" is a good option (and standard). But if you know someone stole your iPhone you might want to try something more, "I know you stole my iPhone, the police are on the way."
Threatening the police action can shake the thief and either force them to release the iPhone and run or call you to confirm their innocence and arrange for the iPhone to be returned. They can also turn off the iPhone and leave their current location until they figure out what to do with it, so be careful what you write.
When done, press or click "Done."
After selecting "Ready", Lost Mode is activated and it will unlock your device and stop anyone without your password from using the Message Center, Control Center and Widgets from the lock screen. It can also be used to shut down Apple Pay.
The message and phone number you selected will be displayed on the lock screen until either your iPhone password is set (Disabled Lost Mode) or the battery runs out. The phone number will not only appear on the screen, but your iPhone will also allow the one who chooses to dial that number directly from the device by pressing a large green "Ring" button.
You will automatically subscribe to email updates when the lost iPhone site changes so you can always keep track of where it is and decide whether it is time or not to dry the device or not.
At any time you can log in again in Find My iPhone and select the "Lost Mode" tool to update the phone number and / or message. Hit "Done" when you're done. You can also subscribe to site updates via e-mail and stop the omission mode in this way.
While we are on the subject, the iPhone battery is not necessarily unauthorized for good security. In fact, Apple has a tool that you can use to send your iPhone's last known location when the device is approaching a low battery door. It is a useful feature that can only save your iPhone if it is missing five percent.
This article has been produced under the Gadget Hack's special coverage of smartphone privacy and security. Check out the entire privacy and security series.
More information: Use your iPhone when the battery is dead