3D 触摸/强制触摸实现

Question

我们如何实现 3D 触摸来检查用户是否点击UIView 或强制触摸UIView？

有没有办法使用UIGestureRecognize 或仅使用UITouch 来做到这一点？

Answer 1

您可以在没有指定手势识别器的情况下执行此操作。您无需调整 touchesEnded 和 touchesBegan 方法，只需调整 touchesMoved 即可获得正确的值。从开始/结束获取 uitouch 的力量将返回奇怪的值。

UITouch *touch = [touches anyObject];

CGFloat maximumPossibleForce = touch.maximumPossibleForce;
CGFloat force = touch.force;
CGFloat normalizedForce = force/maximumPossibleForce;

然后，设置一个力阈值并将 normalizedForce 与此阈值进行比较（0.75 对我来说似乎很好）。

Answer 2

3D Touch 属性are available on UITouch objects。

您可以通过覆盖UIView 的touchesBegan: 和touchesMoved: 方法来实现这些功能。不确定你在touchesEnded: 看到了什么。

如果您愿意创建新的手势识别器，您可以完全访问 UIGestureRecognizerSubclass 中公开的 UITouches。

我不确定如何在传统的UIGestureRecognizer 中使用 3D 触摸属性。也许通过UIGestureRecognizerDelegate 协议的gestureRecognizer:shouldReceiveTouch: 方法。

Answer 3

在 Swift 4.2 和 iOS 12 中，解决问题的一种可能方法是创建 UIGestureRecognizer 的自定义子类来处理 Force Touch，并将其添加到 UITapGestureRecognizer 旁边的视图中。下面的完整代码展示了如何实现它：

ViewController.swift

import UIKit

class ViewController: UIViewController {

    let redView = UIView()
    lazy var tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(tapHandler))
    lazy var forceTouchGestureRecognizer = ForceTouchGestureRecognizer(target: self, action: #selector(forceTouchHandler))

    override func viewDidLoad() {
        super.viewDidLoad()

        redView.backgroundColor = .red    
        redView.addGestureRecognizer(tapGestureRecognizer)

        view.addSubview(redView)
        redView.translatesAutoresizingMaskIntoConstraints = false
        redView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        redView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        redView.widthAnchor.constraint(equalToConstant: 100).isActive = true
        redView.heightAnchor.constraint(equalToConstant: 100).isActive = true
    }

    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)

        if traitCollection.forceTouchCapability == UIForceTouchCapability.available {
            redView.addGestureRecognizer(forceTouchGestureRecognizer)
        } else  {
            // When force touch is not available, remove force touch gesture recognizer.
            // Also implement a fallback if necessary (e.g. a long press gesture recognizer)
            redView.removeGestureRecognizer(forceTouchGestureRecognizer)
        }
    }

    @objc func tapHandler(_ sender: UITapGestureRecognizer) {
        print("Tap triggered")
    }

    @objc func forceTouchHandler(_ sender: ForceTouchGestureRecognizer) {
        UINotificationFeedbackGenerator().notificationOccurred(.success)
        print("Force touch triggered")
    }

}

ForceTouchGestureRecognizer.swift

import UIKit.UIGestureRecognizerSubclass

@available(iOS 9.0, *)
final class ForceTouchGestureRecognizer: UIGestureRecognizer {

    private let threshold: CGFloat = 0.75

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesBegan(touches, with: event)
        if let touch = touches.first {
            handleTouch(touch)
        }
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)
        if let touch = touches.first {
            handleTouch(touch)
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesEnded(touches, with: event)
        state = UIGestureRecognizer.State.failed
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesCancelled(touches, with: event)
        state = UIGestureRecognizer.State.failed
    }

    private func handleTouch(_ touch: UITouch) {
        guard touch.force != 0 && touch.maximumPossibleForce != 0 else { return }

        if touch.force / touch.maximumPossibleForce >= threshold {
            state = UIGestureRecognizer.State.recognized
        }
    }

}

---

来源：

• GitHub / FlexMonkey - DeepPressGestureRecognizer

• GitHub / ashleymills - ForceTouchGestureRecognizer

• Apple Developer Documentation - Implementing a Discrete Gesture Recognizer

Answer 4

我创建了一个模拟 Apple Mail 应用程序行为的 UIGestureRecognizer。在 3D 触摸时，它以一个短的单脉冲振动开始，然后是一个可选的辅助动作 (hardTarget)，并在初始按下后不久通过硬按下调用脉冲。

改编自https://github.com/FlexMonkey/DeepPressGestureRecognizer

变化：

• 3D 触摸振动脉冲类似于 iOS 系统行为
• 必须先触摸才能结束，例如 Apple 邮件应用程序
• 阈值默认为系统默认级别
• 硬触摸触发类似邮件应用的 hardAction 调用

注意：我添加了未记录的系统声音 k_PeakSoundID，但如果您对使用超出记录范围的常数感到不舒服，请随时将其关闭。多年来，我一直在使用具有未公开常量的系统声音，但欢迎您使用 vibrateOnDeepPress 属性关闭振动脉冲。

import UIKit
import UIKit.UIGestureRecognizerSubclass
import AudioToolbox

class DeepPressGestureRecognizer: UIGestureRecognizer {
    var vibrateOnDeepPress = true
    var threshold: CGFloat = 0.75
    var hardTriggerMinTime: TimeInterval = 0.5

    var onDeepPress: (() -> Void)?

    private var deepPressed: Bool = false {
        didSet {
            if (deepPressed && deepPressed != oldValue) {
                onDeepPress?()
            }
        }
    }

    private var deepPressedAt: TimeInterval = 0
    private var k_PeakSoundID: UInt32 = 1519
    private var hardAction: Selector?
    private var target: AnyObject?

    required init(target: AnyObject?, action: Selector, hardAction: Selector? = nil, threshold: CGFloat = 0.75) {
        self.target = target
        self.hardAction = hardAction
        self.threshold = threshold

        super.init(target: target, action: action)
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        if let touch = touches.first {
            handle(touch: touch)
        }
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        if let touch = touches.first {
            handle(touch: touch)
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesEnded(touches, with: event)
        state = deepPressed ? UIGestureRecognizerState.ended : UIGestureRecognizerState.failed
        deepPressed = false
    }

    private func handle(touch: UITouch) {
        guard let _ = view, touch.force != 0 && touch.maximumPossibleForce != 0 else {
            return
        }

        let forcePercentage = (touch.force / touch.maximumPossibleForce)
        let currentTime = Date.timeIntervalSinceReferenceDate

        if !deepPressed && forcePercentage >= threshold {
            state = UIGestureRecognizerState.began

            if vibrateOnDeepPress {
                AudioServicesPlaySystemSound(k_PeakSoundID)
            }

            deepPressedAt = Date.timeIntervalSinceReferenceDate
            deepPressed = true

        } else if deepPressed && forcePercentage <= 0 {
            endGesture()

        } else if deepPressed && currentTime - deepPressedAt > hardTriggerMinTime && forcePercentage == 1.0 {
            endGesture()

            if vibrateOnDeepPress {
                AudioServicesPlaySystemSound(k_PeakSoundID)
            }

            //fire hard press
            if let hardAction = self.hardAction, let target = self.target {
                _ = target.perform(hardAction, with: self)
            }
        }
    }

    func endGesture() {
        state = UIGestureRecognizerState.ended
        deepPressed = false
    }
}

// MARK: DeepPressable protocol extension
protocol DeepPressable {
    var gestureRecognizers: [UIGestureRecognizer]? {get set}

    func addGestureRecognizer(gestureRecognizer: UIGestureRecognizer)
    func removeGestureRecognizer(gestureRecognizer: UIGestureRecognizer)

    func setDeepPressAction(target: AnyObject, action: Selector)
    func removeDeepPressAction()
}

extension DeepPressable {

    func setDeepPressAction(target: AnyObject, action: Selector) {
        let deepPressGestureRecognizer = DeepPressGestureRecognizer(target: target, action: action, threshold: 0.75)
        self.addGestureRecognizer(gestureRecognizer: deepPressGestureRecognizer)
    }

    func removeDeepPressAction() {
        guard let gestureRecognizers = gestureRecognizers else { return }

        for recogniser in gestureRecognizers where recogniser is DeepPressGestureRecognizer {
            removeGestureRecognizer(gestureRecognizer: recogniser)
        }
    }
}

Answer 5

我这样做的方式是结合使用UITapGestureRecognizer（Apple 提供）和DFContinuousForceTouchGestureRecognizer（我提供）。

DFContinuousForceTouchGestureRecognizer 很好，因为它提供了有关压力变化的持续更新，因此您可以在用户改变压力时执行诸如增强视图之类的操作，而不是单个事件。如果您只想要一个事件，您可以忽略 DFContinuousForceTouchDelegate 中的所有内容，除了 - (void) forceTouchRecognized 回调。

https://github.com/foggzilla/DFContinuousForceTouchGestureRecognizer

您可以下载这个并在支持力压的设备上运行示例应用，看看感觉如何。

在您的 UIViewController 中执行以下操作：

- (void)viewDidLoad {
    [super viewDidLoad];
    _forceTouchRecognizer = [[DFContinuousForceTouchGestureRecognizer alloc] init];
    _forceTouchRecognizer.forceTouchDelegate = self;

    //here to demonstrate how this works alonside a tap gesture recognizer
    _tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)];

    [self.imageView addGestureRecognizer:_tapGestureRecognizer];
    [self.imageView addGestureRecognizer:_forceTouchRecognizer];
}

为点击手势实现选择器

#pragma UITapGestureRecognizer selector

- (void)tapped:(id)sender {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [[[UIAlertView alloc] initWithTitle:@"Tap" message:@"YEAH!!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil] show];
    });
}

实现强制触摸的委托协议：

#pragma DFContinuousForceTouchDelegate

- (void)forceTouchRecognized:(DFContinuousForceTouchGestureRecognizer *)recognizer {
    self.imageView.transform = CGAffineTransformIdentity;
    [self.imageView setNeedsDisplay];
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [[[UIAlertView alloc] initWithTitle:@"Force Touch" message:@"YEAH!!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil] show];
    });
}

- (void)forceTouchRecognizer:(DFContinuousForceTouchGestureRecognizer *)recognizer didStartWithForce:(CGFloat)force maxForce:(CGFloat)maxForce {
    CGFloat transformDelta = 1.0f + ((force/maxForce) / 3.0f);
    self.imageView.transform = CGAffineTransformMakeScale(transformDelta, transformDelta);
    [self.imageView setNeedsDisplay];
}

- (void) forceTouchRecognizer:(DFContinuousForceTouchGestureRecognizer *)recognizer didMoveWithForce:(CGFloat)force maxForce:(CGFloat)maxForce {
    CGFloat transformDelta = 1.0f + ((force/maxForce) / 3.0f);
    self.imageView.transform = CGAffineTransformMakeScale(transformDelta, transformDelta);
    [self.imageView setNeedsDisplay];
}

- (void)forceTouchRecognizer:(DFContinuousForceTouchGestureRecognizer *)recognizer didCancelWithForce:(CGFloat)force maxForce:(CGFloat)maxForce  {
    self.imageView.transform = CGAffineTransformIdentity;
    [self.imageView setNeedsDisplay];
}

- (void)forceTouchRecognizer:(DFContinuousForceTouchGestureRecognizer *)recognizer didEndWithForce:(CGFloat)force maxForce:(CGFloat)maxForce  {
    self.imageView.transform = CGAffineTransformIdentity;
    [self.imageView setNeedsDisplay];
}

- (void)forceTouchDidTimeout:(DFContinuousForceTouchGestureRecognizer *)recognizer {
    self.imageView.transform = CGAffineTransformIdentity;
    [self.imageView setNeedsDisplay];
}

请注意，这仅在支持强制触摸的设备上有用。

此外，如果您在 iOS 8 或更低版本上运行，则不应将 DFContinuousForceTouchGestureRecognizer 添加到视图中，因为它使用 UITouch 上的新 force 属性，仅在 iOS 9 中可用。

如果您在 iOS 8 上添加它会崩溃，因此如果您支持的版本早于 iOS 9，请根据您运行的 iOS 版本有条件地添加此识别器。