在2個固定點之間滑動UIView

Question

我試圖讓UIView幻燈片在2點之間滑動。 我嘗試使用UIPanGestureRecognizer。 滑動很好，但是當視圖到達極限點時，會有顛簸的跳動。 這不順利。 這是我的手勢功能：

    func wasDragged(gestureRecognizer: UIPanGestureRecognizer) {
    if gestureRecognizer.state == UIGestureRecognizerState.began || gestureRecognizer.state == UIGestureRecognizerState.changed {
        let translation = gestureRecognizer.translation(in: self.view)
        print(gestureRecognizer.view!.center.x)
        if(gestureRecognizer.view!.center.x <= self.view.frame.width) && (gestureRecognizer.view!.center.x >= self.view.frame.width - 100) {
            gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y:  gestureRecognizer.view!.center.y)
        }else if (gestureRecognizer.view!.center.x > self.view.frame.width){
            gestureRecognizer.view!.center = CGPoint(x: self.view.frame.width, y: gestureRecognizer.view!.center.y)
        }else if (gestureRecognizer.view!.center.x < self.view.frame.width - 100){
            gestureRecognizer.view!.center = CGPoint(x: self.view.frame.width - 100, y: gestureRecognizer.view!.center.y)
        }

        gestureRecognizer.setTranslation(CGPoint(x: 0,y: 0), in: self.view)
    }


}

有什么幫助嗎？ 謝謝。

Answer 1

您的問題是您正在查看視圖的當前位置，而不是在應用當前移動后的視圖位置。

我通過引入newx修復了您的代碼，其中newx顯示了視圖試圖移動到的位置。 那就是您要限制的值。

@IBAction func wasDragged(gestureRecognizer: UIPanGestureRecognizer) {
    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
        let translation = gestureRecognizer.translation(in: self.view)
        print(gestureRecognizer.view!.center.x)
        let newx = gestureRecognizer.view!.center.x + translation.x

        if(newx <= self.view.frame.width) && (newx >= self.view.frame.width - 100) {
            gestureRecognizer.view!.center = CGPoint(x: newx, y:  gestureRecognizer.view!.center.y)
        }else if (newx > self.view.frame.width){
            gestureRecognizer.view!.center = CGPoint(x: self.view.frame.width, y: gestureRecognizer.view!.center.y)
        }else if (newx < self.view.frame.width - 100){
            gestureRecognizer.view!.center = CGPoint(x: self.view.frame.width - 100, y: gestureRecognizer.view!.center.y)
        }

        gestureRecognizer.setTranslation(CGPoint(x: 0,y: 0), in: self.view)
    }
}

---

您可能還想考慮對最終setTranslation調用的更改。 如果用戶試圖在視圖已達到其左極限時向左拖動，然后（不松開手指）改變方向並向右移動，即使他們的手指不再在視圖上，您​​的代碼也會將視圖向右移動。

進行以下更改后，視圖將不會向右移動，直到用戶的手指回到原始觸摸點為止：

gestureRecognizer.setTranslation(CGPoint(x: newx - gestureRecognizer.view!.center.x ,y: 0), in: self.view)

試試看，看看你喜歡哪個。