swift : 平滑 UIView 的平移与 iOS 控制面板完全一样（跟随用户手指，使用平移）

Question

我想像 iOS 中的控制中心一样用手指从下向上移动 UIView，尤其是 "smoothing" 与 [=22= 中的控制中心相同的移动方式] ] （速度看起来是有界的，当速度很高时，手指不需要走得太远就可以使 UIView 移动到顶部等）。我的问题是：有没有我可以使用的任何预设或库，而不是自己进行自定义和不精确的计算？我不太擅长制作这种 "smooth" 效果，也许 UIKit 提供了一些可以在 panGestureRecognizer 处理程序中使用的东西来平滑 sender.translation 之后的移动转换？

现在我的 gestureRecognizer 处理程序是：

var y = sender.translation(in: view).y
let vy = sender.velocity(in: view).y

// we need to move constraintHeightInfoView.constant
// this is the height of my "ios control panel"

// i noticed the ios control panel move less if user tries 
// to move it out of screen bounds, so i'm first calculating 
// how much we are out of bound, in order to know "how much" 
// we will reduce velocity
var outofbound:CGFloat = 0
if(constraintHeightInfoView.constant < minH)
{
    outofbound = minH - constraintHeightInfoView.constant
}
else if(constraintHeightInfoView.constant > maxH)
{
    outofbound = constraintHeightInfoView.constant - maxH
}

// velocity target in pt/s
// i noticed the smooth effect in ios control panel includes 
// a velocity bound : if user pulls very fast the control panel, 
// it is not following the user finger, but it's a bit slower : 
// so there is a "vmax". When user release, i guess this vmax is 
// used for the final animation too 
let vtarget:CGFloat = 300 

print("\(y), \(vy), ofb : \(outofbound)")


// Here i'm lost : im trying to say : 
// if velocity above vtarget, reduce y so it match vtarget
if(abs(vy) > vtarget) {
    let dv = abs(vy) - vtarget
    y = // ????
}





switch sender.state {
    case .began, .changed :
    if case .began = sender.state {
        initialY = constraintHeightInfoView.constant
    }

    let newH = (expandInfoViewInitialY ?? minH) - y

    constraintHeightInfoView.constant = newH

    view.layoutIfNeeded()

case .ended :

    let heightTo:CGFloat
    let blurAlpha:CGFloat
    // 250 is the middle between top position and 
    // bottom position : if velocity is high, dont need to pull 
    // a lot to proceed the final release animation
    // if vy is 3000, even very small movement proceed the 
    // animation. Otherwise, if very slow movement, 
    // user needs to go at least at the middle between top and bottom (250)
    if(constraintHeightInfoView.constant > 250 - (-vy/300) * 50)
    {
        heightTo = maxH
        blurAlpha = 1
    }
    else
    {
        heightTo = minH
        blurAlpha = 0
    }


    // time of animation depends on remaining distance to bottom/top
    let dy = abs(self.constraintHeightInfoView.constant - heightTo)


    var t = dy / vtarget

    print("end : d:\(dy), t:\(t)")
    UIView.animate(withDuration:TimeInterval(t), delay:0,options:[.curveEaseOut], animations :{
        self.constraintHeightInfoView.constant = heightTo
        self.viewInfoBlurEffect.alpha = blurAlpha
        self.view.layoutIfNeeded()
    })

default :
    break
}

尽管如此，我的转换仍然远不像 Apple Control Center 的那样...

Answer 1

如果您将其设置为从下到上和从上到下的动画效果，您将获得更满意的体验。现在 "freeze" 它并通过 UIViewPropertyAnimator 从平移手势识别器连接到它。这使它成为一个交互式动画。

例如，如果用户拖动超过一定数量，这将允许您 "finish" 动画。而且你将能够通过同一个动画师同时完成 tap-to-dismiss 和 drag-to-dismiss。

swift : 平滑 UIView 的平移与 iOS 控制面板完全一样（跟随用户手指，使用平移）

swift : smoothing translation of UIView exactly as iOS control panel (following user finger, using pan)

swift

uipangesturerecognizer