Use iPhone's Proximity Sensor

Question

Hi ✋ I'm trying to build an app with SwiftUI, and I'm completely new to coding. I want to use iPhone's proximity sensor as a feature in my app.

This is not what I actually want, but to make it simple:

Say there is a number shown on the screen. Whenever I cover the iPhone's proximity sensor with my hand, the number is increased by one. theNumber += 1

import SwiftUI

struct ContentView: View {
    @State private var theNumber: Int = 0

    var body: some View {
        Text("\(theNumber)")
    }
}

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Posted by

AmeenMouazzen

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Answer 1

You can retrieve the proximityState value from the current UIDevice and detect when it changes. You need to enable proximity monitoring first and I suggest doing that in your main App struct.

// in main App struct
init() {
    UIDevice.current.isProximityMonitoringEnabled = true
}

struct ContentView: View {
    @State private var theNumber = 0

    var body: some View {
        Text("\(theNumber)")
            .onReceive(NotificationCenter.default.publisher(for: UIDevice.proximityStateDidChangeNotification)) { _ in
                if UIDevice.current.proximityState {
                    // sensor is close to user
                    // true is "near", false is "far"

                    theNumber += 1
                }
            }
    }
}

‎

Things to Note

The sensor detects objects up to 10 cm away.
When the sensor detects an object that is close, the screen turns off.
There is no single point where the proximity state switches between "near" and "far", but instead a buffer range.
When the state is "far", the object must be up to 5 cm from the sensor in order to change the state to "near".
When the state is "near", the object must be at least 10 cm from the sensor in order to change the state to "far".

Posted by

BabyJ

Hi BabyJ,

the code looks good and compiles but the Notification Center does not publish anything.

Device: iPhone 13 Pro Operating System: iOS 17

Is it still working for you or do you have an idea on what the issue might be?

Best, Jonas

—
Jonas54

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Answer 2

You can retrieve the proximityState value from the current UIDevice and detect when it changes. You need to enable proximity monitoring first and I suggest doing that in your main App struct.

// in main App struct
init() {
    UIDevice.current.isProximityMonitoringEnabled = true
}

struct ContentView: View {
    @State private var theNumber = 0

    var body: some View {
        Text("\(theNumber)")
            .onReceive(NotificationCenter.default.publisher(for: UIDevice.proximityStateDidChangeNotification)) { _ in
                if UIDevice.current.proximityState {
                    // sensor is close to user
                    // true is "near", false is "far"

                    theNumber += 1
                }
            }
    }
}

‎

Things to Note

The sensor detects objects up to 10 cm away.
When the sensor detects an object that is close, the screen turns off.
There is no single point where the proximity state switches between "near" and "far", but instead a buffer range.
When the state is "far", the object must be up to 5 cm from the sensor in order to change the state to "near".
When the state is "near", the object must be at least 10 cm from the sensor in order to change the state to "far".

Posted by

BabyJ

Hi BabyJ,

the code looks good and compiles but the Notification Center does not publish anything.

Device: iPhone 13 Pro Operating System: iOS 17

Is it still working for you or do you have an idea on what the issue might be?

Best, Jonas

—
Jonas54

Add a Comment

Answer 3

Thanks for this

Posted by

Hdhjhc

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Answer 4

I copied this code and ran it on my iPhone 13. The number does not change. I did confirm that my sensor was working by calling someone to see if my screen turns off.

Posted by

Davu

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Use iPhone's Proximity Sensor

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