Question

我正在尝试设计一个界面，在该界面上，点击可以淡入文本，然后淡出文本，但是在屏幕上向上拖动两个手指可以使其变亮，而向下拖动两个手指可以使屏幕变暗。我已经使文本淡入和淡出，但是我似乎无法使亮度功能正常工作。该应用程序正在构建中，但是两根手指的手势根本不起作用。

我尝试插入发现的here代码。

我尝试了Stack Overflow上发现的其他几种方法，例如也发现了here，但没有运气。

更新：我根据@rmaddy和@ leo-dabus的反馈意见进行了一些更改。当我在模拟器或iPhone上平移时，仍然什么也没有发生。我不确定是否应该使用“ recognizer.state”而不是“ sender.state”。我确定我会犯很多新手错误。我什至在正确的位置上有平移手势的代码吗？这是我现在拥有的：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Hide text on launch
        self.text.alpha = 0

    }
    // Introducing: The text!
    @IBOutlet weak var text: UITextView!

    // Show text upon tap of gesture recognizer
    @IBAction func tap(_ sender: UITapGestureRecognizer) {
            // fade in
            UIView.animate(withDuration: 0.5, animations: {
                self.text.alpha = 1.0
            }) { (finished) in
                // fade out
                UIView.animate(withDuration: 4.0, animations: {
                    self.text.alpha = 0.0
                })
            }
        }


    @IBAction func twoFingerPan(_ sender: UIPanGestureRecognizer) {
        if sender.state == UIPanGestureRecognizer.State.changed || sender.state == UIPanGestureRecognizer.State.ended {
            let velocity:CGPoint = sender.velocity(in: self.view)
            if velocity.y > 0 {
                UIScreen.main.brightness -= 0.03
            }
            else {
                UIScreen.main.brightness += 0.03
                }
            }
        }
    }

Answer 1

我建议创建几个手势识别器。像这样：

fileprivate func setGestureRecognizers() {
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(tap(_:)))
    tapGesture.delegate = self as? UIGestureRecognizerDelegate
    tapGesture.numberOfTapsRequired = 1
    view.addGestureRecognizer(tapGesture)

    let panGesture = UIPanGestureRecognizer.init(target: self, action: #selector(twoFingerPan(_:)))
    panGesture.delegate = self as? UIGestureRecognizerDelegate
    panGesture.minimumNumberOfTouches = 1
    view.addGestureRecognizer(panGesture)
}

在viewDidLoad上调用此方法：

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    // Hide text on launch
    self.text.alpha = 0

    setGestureRecognizers()
}

然后，我更改了一些方法，因为我使用代码而不是使用故事板设置了手势识别器，因此我摆脱了@IBAction并添加了@objc。另外，我也在手机上进行了测试，并比较了velocity.y > 0的手势对手指的移动过于敏感，因此将其更改为0.4。

// Show text upon tap of gesture recognizer
@objc func tap(_ sender: UITapGestureRecognizer) {
    // fade in
    UIView.animate(withDuration: 0.5, animations: {
        self.text.alpha = 1.0
    }) { (finished) in
        // fade out
        UIView.animate(withDuration: 4.0, animations: {
            self.text.alpha = 0.0
        })
    }
}

@objc func twoFingerPan(_ sender: UIPanGestureRecognizer) {
    if sender.state == UIPanGestureRecognizer.State.changed || sender.state == UIPanGestureRecognizer.State.ended {
        let velocity:CGPoint = sender.velocity(in: self.view)
        if velocity.y > 0.4 {
            UIScreen.main.brightness -= CGFloat(0.03)
        }
        else {
            UIScreen.main.brightness += CGFloat(0.03)
        }
    }
}

通过点击来控制文本字母，并通过平移手势来控制屏幕亮度

1 个答案: