Check if 3D touch is supported and enabled on the iOS9 device

Question

I tried to access the trait collection and check "forceTouchCapability", but "forceTouchCapability" simply checks to see if the device is iOS 9.0 or greater.

So, this means that on any device with iOS 9, force touch is 'available'. I need to a way to check if 3D touch is actually supported on the users device (iPhone 6s) and I need to make sure that the 3D Touch option is actually enabled in the accessibility settings.

Incompressible

That's bad news - have you tried it on the 9.1 beta? – Hayton

No, we are adding 3D touch capability to an app we are going to be releasing in a few days, so we are aiming for 9.0. Using Xcode 7.0. – Incompressible

Maybe I am doing something wrong. – Incompressible

From what I understand, you are on the right track with accessing the trait collection and using forceTouchCapability. This link seems helpful/relevant: pinkstone.co.uk/… – Insphere

On what basis are you stating that forceTouchCapability only checks to see if the device is iOS 9 or greater? – Arnone

We have 3 devices - an iPad Air 1 (No 3d touch, running iOS 9.0), iPhone 6 (No 3d touch, running iOS 8.3), iPhone 6s (3d touch, running iOS 9.0). – Incompressible

forceTouchCapability returns: true on iPad, true on iPhone 6s, false on iPhone 6. – Incompressible

I am writing a plugin for a Unity3D game. To get access to the Unity View, I am fetching the last view using this: UIView *UnityView = [[[[UIApplication sharedApplication] keyWindow] subviews] lastObject]; and returning this: [[UnityView traitCollection] forceTouchCapability]; – Incompressible

I think I just realised my error - I am returning forceTouchCapability, assuming it is a 'bool'. It is actually an enum, and I guess it was being cast to a bool - returning true when it equalled '1' (UIForceTouchCapabilityUnavailable = 1) – Incompressible

I was just going to point out that the return value is not a BOOL. – Arnone

Amateur mistake :-) I've answered my own question – Incompressible

Answer 1

I was accidentally casting forceTouchCapability to a BOOL (using it as a return value to my method that was set to return a boolean). I needed to check if forceTouchCapability was equal to UIForceTouchCapabilityAvailable.

Instead of:

return [[MyView traitCollection] forceTouchCapability];

I need:

return [[MyView traitCollection] forceTouchCapability] == UIForceTouchCapabilityAvailable;

Incompressible

Keep in mind that you need to properly guard this code if your app supports iOS 8.x or earlier in addition to iOS 9. – Arnone

Yep! Thanks, already done :) Ran into that properly already hehe. – Incompressible

swift version #33687140 – Underwater

@Incompressible hey I do not have a 3D touch device I wanted to ask: Although it returns NotAvailable for device not supporting 3D Touch, does it also return NotAvailable for devices with 3D touch but disabled in settings? – Profluent

Answer 2

If you implement this in UIViewController, the timing matters. Checking in viewDidLoad will return Unknown when it will return Available later in the lifecycle.

- (void)traitCollectionDidChange:(nullable UITraitCollection *)previousTraitCollection {
    [self checkForForceTouch];
}

- (void)checkForForceTouch {
    if ([self.traitCollection respondsToSelector:@selector(forceTouchCapability)] &&
        self.traitCollection.forceTouchCapability == UIForceTouchCapabilityAvailable) {
        NSLog(@"Force touch found");
    }
}

Occultation

it 3d touch disable from settings, how to check this – Toadinthehole

@Toadinthehole This method will automatically detect this. – Boloney

Answer 3

Sometimes we want just to have forceTouchCapability value right now synchronously and don't want to wait for traitCollectionDidChange: event. In that case, we can use pretty stupid function like this:

public func forceTouchCapability() -> UIForceTouchCapability {
    return UIApplication.sharedApplication().keyWindow?.rootViewController?.traitCollection.forceTouchCapability ?? .Unknown
}

Perlie

Answer 4

if ([MyView respondsToSelector:@selector(traitCollection)] &&
    [MyView.traitCollection respondsToSelector:@selector(forceTouchCapability)] &&
    MyView.traitCollection.forceTouchCapability == UIForceTouchCapabilityAvailable) {
        return YES;
    }

My point is, if you are supporting iOS 7 and iOS 8 as well, remember to check for both the conditions: [MyView respondsToSelector:@selector(traitCollection)] and [MyView.traitCollection respondsToSelector:@selector(forceTouchCapability)].

If you keep the first check, the app works fine on iOS 7 but crashes on iOS 8. Basically, Apple introduced traitCollection property in iOS 8 but added forceTouchCapability property only in iOS 9.

from UITraitCollection.h:

@property (nonatomic, readonly) UITraitCollection *traitCollection NS_AVAILABLE_IOS(8_0);

@property (nonatomic, readonly) UIForceTouchCapability forceTouchCapability NS_AVAILABLE_IOS(9_0);

PS: Learnt it the hard way, after app started to crash on App Store.

Marlowe

Answer 5

Swift 4.0 and 4.1.

import UIKit

class ViewController: UIViewController {
     override func viewDidLoad() {
        super.viewDidLoad()
        // Check device supports feature
        if self.traitCollection.forceTouchCapability == .available {
        // Enable 3D Touch feature here
         } else {
        // Fall back to other non 3D feature
         }
      }
      override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        // Update the app's 3D Touch support
      if self.traitCollection.forceTouchCapability == .available {
          // Enable 3D Touch feature here
      } else {
          // Fall back to other non 3D feature
      }
    }
  }

Sisal

Answer 6

following Valentin Shergin, updated for swift 4.2 if You need a sync call:

func forceTouchCapability() -> UIForceTouchCapability {
    return UIApplication.shared.keyWindow?.rootViewController?.traitCollection.forceTouchCapability ?? .unknown
}


func hasForceTouchCapability() -> Bool {
    return forceTouchCapability() == .available
}

Phenica