iOS device orientation disregarding orientation lock

Question

I want to query the orientation the iPhone is currently in. Using

[UIDevice currentDevice].orientation

works as long as the device isn't orientation-locked. If it is locked, however, it always responds with the locked orientation, not with the actual orientation of the device.

Is there a high-level way to get the actual device orientation?

Answer 1

Also you can use CoreMotion

Orientation detection algorithm:

• if abs( y ) < abs( x ) your iPhone is in landscape position, look sign of x to detect right or left

• else your iPhone is in portrait position, look sign of y to detect up or upside-down.

• If you are interested in face-up or down, look value of z.

---

import CoreMotion

---

var uMM: CMMotionManager!

override func
viewWillAppear( p: Bool ) {
    super.viewWillAppear( p )
    uMM = CMMotionManager()
    uMM.accelerometerUpdateInterval = 0.2

    //  Using main queue is not recommended. So create new operation queue and pass it to startAccelerometerUpdatesToQueue.
    //  Dispatch U/I code to main thread using dispach_async in the handler.
    uMM.startAccelerometerUpdatesToQueue( NSOperationQueue() ) { p, _ in
        if p != nil {
            println(
                abs( p.acceleration.y ) < abs( p.acceleration.x )
                ?   p.acceleration.x > 0 ? "Right"  :   "Left"
                :   p.acceleration.y > 0 ? "Down"   :   "Up"
            )
        }
    }
}

override func
viewDidDisappear( p: Bool ) {
    super.viewDidDisappear( p )
    uMM.stopAccelerometerUpdates()
}

Answer 2

That functionality is correct. If it always returned the device orientation, even if it was locked, the orientation changed notifications would fire. This would defeat the purpose of the lock.

To answer your question, there is no way to read the raw values from the accelerometer, without using private APIs.

Edit:

After reviewing the documentation, it seems that the UIAccelerometer class provides this data, even when the orientation is locked. This change was applied in iOS 4 and above. Even though you can use this data, you still need to process it to determine the orientation. This is not an easy task as you need to monitor the changes constantly and compare them to older values.

Also, take a look at this guide for handling motion events. This may provide you with another route to determining the orientation.

Answer 3

Set up your view controller or whatever to support the UIAccelerometerProtocol, and start listening for changes (you can set it to 10 hz).

#define kAccelerometerFrequency        10.0 //Hz
-(void)viewDidAppear:(BOOL)animated {
    DLog(@"viewDidAppear");
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    UIAccelerometer* a = [UIAccelerometer sharedAccelerometer];
    a.updateInterval = 1 / kAccelerometerFrequency;
    a.delegate = self;
}

-(void)viewWillDisappear:(BOOL)animated {
    DLog(@"viewWillDisappear");
    UIAccelerometer* a = [UIAccelerometer sharedAccelerometer];
    a.delegate = nil;
    [[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
}

#ifdef DEBUG
+(NSString*)orientationToText:(const UIInterfaceOrientation)ORIENTATION {
    switch (ORIENTATION) {
        case UIInterfaceOrientationPortrait:
            return @"UIInterfaceOrientationPortrait";
        case UIInterfaceOrientationPortraitUpsideDown:
            return @"UIInterfaceOrientationPortraitUpsideDown";
        case UIInterfaceOrientationLandscapeLeft:
            return @"UIInterfaceOrientationLandscapeLeft";
        case UIInterfaceOrientationLandscapeRight:
            return @"UIInterfaceOrientationLandscapeRight";
    }
    return @"Unknown orientation!";
}
#endif

#pragma mark UIAccelerometerDelegate
-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
    UIInterfaceOrientation orientationNew;
    if (acceleration.x >= 0.75) {
        orientationNew = UIInterfaceOrientationLandscapeLeft;
    }
    else if (acceleration.x <= -0.75) {
        orientationNew = UIInterfaceOrientationLandscapeRight;
    }
    else if (acceleration.y <= -0.75) {
        orientationNew = UIInterfaceOrientationPortrait;
    }
    else if (acceleration.y >= 0.75) {
        orientationNew = UIInterfaceOrientationPortraitUpsideDown;
    }
    else {
        // Consider same as last time
        return;
    }

    if (orientationNew == orientationLast)
        return;

    NSLog(@"Going from %@ to %@!", [[self class] orientationToText:orientationLast], [[self class] orientationToText:orientationNew]);
    orientationLast = orientationNew;
}
#pragma mark -

You need to define UIInterfaceOrientation orientationLast as a member variable and you're set.

Answer 4

Handling all 6 orientations

Though we don't often care about FaceUp / FaceDown orientations, they're still important.

Taking them into account leads to a much more appropriate sensitivity for orientation changes, while leaving them out can lead to metastability & hysteresis.

Here's how I handled it -

- (void)startMonitoring
{
    [self.motionManager startAccelerometerUpdatesToQueue:self.opQueue withHandler:^(CMAccelerometerData * _Nullable accelerometerData, NSError * _Nullable error) {

        if (error != nil)
        {
            NSLog(@"Accelerometer error: %@", error);
        }
        else
        {
            float const threshold = 40.0;

            BOOL (^isNearValue) (float value1, float value2) = ^BOOL(float value1, float value2)
            {
                return fabsf(value1 - value2) < threshold;
            };

            BOOL (^isNearValueABS) (float value1, float value2) = ^BOOL(float value1, float value2)
            {
                return isNearValue(fabsf(value1), fabsf(value2));
            };

            float yxAtan = (atan2(accelerometerData.acceleration.y, accelerometerData.acceleration.x)) * 180 / M_PI;
            float zyAtan = (atan2(accelerometerData.acceleration.z, accelerometerData.acceleration.y)) * 180 / M_PI;
            float zxAtan = (atan2(accelerometerData.acceleration.z, accelerometerData.acceleration.x)) * 180 / M_PI;

            UIDeviceOrientation orientation = self.orientation;

            if (isNearValue(-90.0, yxAtan) && isNearValueABS(180.0, zyAtan))
            {
                orientation = UIDeviceOrientationPortrait;
            }
            else if (isNearValueABS(180.0, yxAtan) && isNearValueABS(180.0, zxAtan))
            {
                orientation = UIDeviceOrientationLandscapeLeft;
            }
            else if (isNearValueABS(0.0, yxAtan) && isNearValueABS(0.0, zxAtan))
            {
                orientation = UIDeviceOrientationLandscapeRight;
            }
            else if (isNearValue(90.0, yxAtan) && isNearValueABS(0.0, zyAtan))
            {
                orientation = UIDeviceOrientationPortraitUpsideDown;
            }
            else if (isNearValue(-90.0, zyAtan) && isNearValue(-90.0, zxAtan))
            {
                orientation = UIDeviceOrientationFaceUp;
            }
            else if (isNearValue(90.0, zyAtan) && isNearValue(90.0, zxAtan))
            {
                orientation = UIDeviceOrientationFaceDown;
            }

            if (self.orientation != orientation)
            {
                dispatch_async(dispatch_get_main_queue(), ^{

                    [self orientationDidChange:orientation];
                });
            }
        }
    }];
}

Additionally, I've added a threshold value of 40.0 (instead of 45.0). This makes changes less sensitive, preventing hysteresis at inflection points.

If you only want to react to changes of the main 4 orientations, just do this

if (UIDeviceOrientationIsPortrait(orientation) || UIDeviceOrientationIsLandscape(orientation))
{
     // Do something
}

Answer 5

The UIAccelerometer class continues to function when the device orientation is locked. You'll have to work out your own methods of turning its variables into orientation values, but it shouldn't be especially complicated.

Have a play with Apple's AcceleromoterGraph sample app to see what values the accelerometer outputs in different orientations.

Answer 6

my solution using coremotion,it work even when the device has his orientation locked.

    let motionManager: CMMotionManager = CMMotionManager()

on the did load method

motionManager.deviceMotionUpdateInterval = 0.01
    if motionManager.accelerometerAvailable{
        let queue = NSOperationQueue()
        motionManager.startAccelerometerUpdatesToQueue(queue, withHandler:
            {data, error in

                guard let data = data else{
                    return
                }
                let angle = (atan2(data.acceleration.y,data.acceleration.x))*180/M_PI;

                print(angle)
                if(fabs(angle)<=45){
                    self.orientation = AVCaptureVideoOrientation.LandscapeLeft
                    print("landscape left")
                }else if((fabs(angle)>45)&&(fabs(angle)<135)){

                    if(angle>0){
                        self.orientation = AVCaptureVideoOrientation.PortraitUpsideDown
                        print("portrait upside Down")


                    }else{
                        self.orientation = AVCaptureVideoOrientation.Portrait
                        print("portrait")

                    }
                }else{
                    self.orientation = AVCaptureVideoOrientation.LandscapeRight
                    print("landscape right")

                }


            }
        )
    } else {
        print("Accelerometer is not available")
    }

hope it helps.

Answer 7

Most of the answers are using accelerometer, which is the overall acceleration = user + gravity.

But to get a device orientation, it is more accurate to use the gravity acceleration . Using gravity will prevent the edge case when user moves in a particular direction. To access the gravity, we have to use startDeviceMotionUpdates API instead.

let motionManager = CMMotionManager()
motionManager.startDeviceMotionUpdates(to: OperationQueue()) { (data, error) in
    guard let gravity = data?.gravity else { return }

    let newDeviceOrientation: UIDeviceOrientation
    if abs(gravity.y) < abs(gravity.x) {
        newDeviceOrientation = gravity.x > 0 ? .landscapeRight : .landscapeLeft
    } else {
        newDeviceOrientation = gravity.y > 0 ? .portraitUpsideDown : .portrait
    }
}

Answer 8

Use of CMMotionManager may help, but not the above way. The above logic is not a stable one. I have tested throughly and found that by seeing the values of acceleration.x/y/z are not helping to determine the orientation.

Instead, I got a way to find the orientation WRT the angle ie float angle = (atan2(accelerometerData.acceleration.y,accelerometerData.acceleration.x))*180/M_PI;

And for orientation,- if(fabs(angle<=45)currOrientation=UIDeviceOrientationLandscapeRight; else if((fabs(angle)>45)&&(fabs(angle)<135))currOrientation=((angle>0)?UIDeviceOrientationPortraitUpsideDown:UIDeviceOrientationPortrait); else currOrientation = UIDeviceOrientationLandscapeLeft;

This might come handy for someone, though this doesn't help me to find 2 other orientations ie UIDeviceOrientationFaceUp & UIDeviceOrientationFaceDown .

Answer 9

Using Satachito's great answer here is code which will also detect if the device is face up or face down

import CoreMotion

---

var mm: CMMotionManager!

init() {
    self.mm = CMMotionManager()
    self.mm.accelerometerUpdateInterval = 0.2
}

public func startOrientationUpdates() {
    //  Using main queue is not recommended. So create new operation queue and pass it to startAccelerometerUpdatesToQueue.
    //  Dispatch U/I code to main thread using dispach_async in the handler.
    self.mm.startAccelerometerUpdates( to: OperationQueue() ) { p, _ in
        if let p = p {
            if(p.acceleration.x > -0.3 && p.acceleration.x < 0.3 && p.acceleration.z < -0.95) {
                print("face up")
            }
            else if(p.acceleration.x > -0.3 && p.acceleration.x < 0.3 && p.acceleration.z > 0.95) {
                print("face down")
            }
            else {
                print(
                    abs( p.acceleration.y ) < abs( p.acceleration.x )
                        ?   p.acceleration.x > 0 ? "Right"  :   "Left"
                        :   p.acceleration.y > 0 ? "Down"   :   "Up"
                )
            }

        }
    }
}

public func endOrientationUpdates() {
    self.mm.stopAccelerometerUpdates()
}

Answer 10

Here is an example of detect device rotation and return UIDeviceOrientation. This solution using CoreMotion and works in all cases.

Example

let orientationManager = APOrientationManager()
orientationManager.delegate = self
/// start detect rotation
orientationManager.startMeasuring()

/// get current interface orientation
let orientation = orientationManager.currentInterfaceOrientation()
print(orientation.rawValue)

/// stop detect rotation
orientationManager.stopMeasuring()
orientationManager.delegate = nil

conform delegate

extension ViewController: APOrientationManagerDelegate {
    func didChange(deviceOrientation: UIDeviceOrientation) {
        /// update UI in main thread
    }
}

APOrientationManager.swift

import Foundation
import CoreMotion
import AVFoundation
import UIKit

protocol APOrientationManagerDelegate: class {
    func didChange(deviceOrientation: UIDeviceOrientation)
}

class APOrientationManager {

    private let motionManager = CMMotionManager()
    private let queue = OperationQueue()
    private var deviceOrientation: UIDeviceOrientation = .unknown
    weak var delegate: APOrientationManagerDelegate?

    init() {
        motionManager.accelerometerUpdateInterval = 1.0
        motionManager.deviceMotionUpdateInterval = 1.0
        motionManager.gyroUpdateInterval = 1.0
        motionManager.magnetometerUpdateInterval = 1.0
    }

    func startMeasuring() {
        guard motionManager.isDeviceMotionAvailable else {
            return
        }
        motionManager.startAccelerometerUpdates(to: queue) { [weak self] (accelerometerData, error) in
            guard let strongSelf = self else {
                return
            }
            guard let accelerometerData = accelerometerData else {
                return
            }

            let acceleration = accelerometerData.acceleration
            let xx = -acceleration.x
            let yy = acceleration.y
            let z = acceleration.z
            let angle = atan2(yy, xx)
            var deviceOrientation = strongSelf.deviceOrientation
            let absoluteZ = fabs(z)

            if deviceOrientation == .faceUp || deviceOrientation == .faceDown {
                if absoluteZ < 0.845 {
                    if angle < -2.6 {
                        deviceOrientation = .landscapeRight
                    } else if angle > -2.05 && angle < -1.1 {
                        deviceOrientation = .portrait
                    } else if angle > -0.48 && angle < 0.48 {
                        deviceOrientation = .landscapeLeft
                    } else if angle > 1.08 && angle < 2.08 {
                        deviceOrientation = .portraitUpsideDown
                    }
                } else if z < 0 {
                    deviceOrientation = .faceUp
                } else if z > 0 {
                    deviceOrientation = .faceDown
                }
            } else {
                if z > 0.875 {
                    deviceOrientation = .faceDown
                } else if z < -0.875 {
                    deviceOrientation = .faceUp
                } else {
                    switch deviceOrientation {
                    case .landscapeLeft:
                        if angle < -1.07 {
                            deviceOrientation = .portrait
                        }
                        if angle > 1.08 {
                            deviceOrientation = .portraitUpsideDown
                        }
                    case .landscapeRight:
                        if angle < 0 && angle > -2.05 {
                            deviceOrientation = .portrait
                        }
                        if angle > 0 && angle < 2.05 {
                            deviceOrientation = .portraitUpsideDown
                        }
                    case .portraitUpsideDown:
                        if angle > 2.66 {
                            deviceOrientation = .landscapeRight
                        }
                        if angle < 0.48 {
                            deviceOrientation = .landscapeLeft
                        }
                    case .portrait:
                        if angle > -0.47 {
                            deviceOrientation = .landscapeLeft
                        }
                        if angle < -2.64 {
                            deviceOrientation = .landscapeRight
                        }
                    default:
                        if angle > -0.47 {
                            deviceOrientation = .landscapeLeft
                        }
                        if angle < -2.64 {
                            deviceOrientation = .landscapeRight
                        }
                    }
                }
            }
            if strongSelf.deviceOrientation != deviceOrientation {
                strongSelf.deviceOrientation = deviceOrientation
                strongSelf.delegate?.didChange(deviceOrientation: deviceOrientation)
            }
        }
    }

    func stopMeasuring() {
        motionManager.stopAccelerometerUpdates()
    }

    func currentInterfaceOrientation() -> AVCaptureVideoOrientation {
        switch deviceOrientation {
        case .portrait:
            return .portrait
        case .landscapeRight:
            return .landscapeLeft
        case .landscapeLeft:
            return .landscapeRight
        case .portraitUpsideDown:
            return .portraitUpsideDown
        default:
            return .portrait
        }
    }
}