UIPanGestureRecognizer 的翻译在 iPad 中始终为零答案

【问题标题】：Translation of UIPanGestureRecognizer is always zero in iPadUIPanGestureRecognizer 的翻译在 iPad 中始终为零
【发布时间】：2017-05-15 19:53:46
【问题描述】：

UIPanGestureRecognizer 有一个非常奇怪的问题。我使用识别器在 SceneView 中旋转 3D 模型或相机。

识别器适用于 iPhone。但是，如果我在 iPad（物理设备或模拟器）上启动应用程序，识别器会被识别，但翻译始终为零。

这是为什么呢？再次，iPhone 运行良好。这是一个错误吗？

识别器创建：

// Model Rotation
let rotationRecognizer = UIPanGestureRecognizer(target: self, action: #selector(self.rotationRecognized(sender:)))
rotationRecognizer.minimumNumberOfTouches = 1
rotationRecognizer.maximumNumberOfTouches = 1
self.view.addGestureRecognizer(rotationRecognizer)

事件处理程序：

// MARK: Rotation of Model and Camera
func rotationRecognized(sender: UIPanGestureRecognizer) {
    if sender.state == .began {
        let translation = sender.translation(in: self.sceneView)
        Swift.print(translation)

        if abs(translation.x) > 0 {
            self.rotationMode = .model
        } else if abs(translation.y) > 0 {
            self.rotationMode = .camera
        }
    } else if sender.state == .changed {
        let translation = sender.translation(in: self.sceneView)

        if self.rotationMode == .model {
            if rootNode != nil {
                var newAngleY = Float(translation.x / 4) * Float(M_PI / 180.0)
                newAngleY += currentYAngle
                rootNode!.eulerAngles.y = newAngleY
            }
        } else if self.rotationMode == .camera {
            if cameraNode != nil {
                var newAngle = Float(translation.y / 4) * Float(M_PI / 180.0)

                if translation.y < 0 { // Up 
                    if Math.toDegrees(Double(newAngle + currentXAngle)) < -70 {
                        return
                    }
                } else if translation.y > 0 { // Down 
                    if Math.toDegrees(Double(newAngle + currentXAngle)) > -10 {
                        return
                    }
                }

                newAngle += currentXAngle
                cameraNode!.eulerAngles.x = newAngle
            }
        }
    } else if sender.state == .ended {
        if self.rotationMode == .model {
            if rootNode != nil {
                currentYAngle = rootNode!.eulerAngles.y
            }
        } else if self.rotationMode == .camera {
            if cameraNode != nil {
                currentXAngle = cameraNode!.eulerAngles.x
            }
        }

        self.rotationMode = .none
    }
}

【问题讨论】：

标签： swift rotation scenekit uipangesturerecognizer

【解决方案1】：

// MARK: Rotation of Model and Camera
func rotationRecognized(sender: UIPanGestureRecognizer)
{
    if sender.state == .ended
    {
        if self.rotationMode == .model
        {
            if rootNode != nil
            {
                currentYAngle = rootNode!.eulerAngles.y
            }
        }
        else if self.rotationMode == .camera
        {
            if cameraNode != nil
            {
                currentXAngle = cameraNode!.eulerAngles.x
            }
        }

        self.rotationMode = .none
        return
    }

    let translation = sender.translation(in: sender.view)

    // Began
    if translation.x == 0 && translation.y == 0 && self.rotationMode == .none
    {
        return
    }
    else
    {
        // First change after recognition
        if self.rotationMode == .none
        {
            if abs(translation.x) > 0
            {
                self.rotationMode = .model
            }
            else if abs(translation.y) > 0
            {
                self.rotationMode = .camera
            }
        }
        else
        {
            if self.rotationMode == .model
            {
                if rootNode != nil
                {
                    var newAngleY = Float(translation.x / 4) * Float(M_PI / 180.0)
                    newAngleY += currentYAngle
                    rootNode!.eulerAngles.y = newAngleY
                }
            }
            else if self.rotationMode == .camera
            {
                if cameraNode != nil
                {
                    var newAngle = Float(translation.y / 4) * Float(M_PI / 180.0)

                    if translation.y < 0 // Up
                    {
                        if Math.toDegrees(Double(newAngle + currentXAngle)) < -70
                        {
                            return
                        }
                    }
                    else if translation.y > 0 // Down
                    {
                        if Math.toDegrees(Double(newAngle + currentXAngle)) > -10
                        {
                            return
                        }
                    }

                    newAngle += currentXAngle
                    cameraNode!.eulerAngles.x = newAngle
                }
            }
        }
    }
}

【讨论】：