Add bounces property for disabling over-scroll bouncing.

Sources/Pageboy/PageboyScrollDetection.swift

@@ -52,6 +52,10 @@ extension PageboyViewController: UIPageViewControllerDelegate, UIScrollViewDeleg
  //
 
  public func scrollViewDidScroll(_ scrollView: UIScrollView) {
+ guard self.updateContentOffsetForBounceIfNeeded(scrollView: scrollView) == false else {
+ return
+ }
+
  guard let currentIndex = self.currentIndex else {
  return
  }
@@ -130,6 +134,10 @@ extension PageboyViewController: UIPageViewControllerDelegate, UIScrollViewDeleg
  self.scrollView(didEndScrolling: scrollView)
  }
 
+ public func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
+ self.updateContentOffsetForBounceIfNeeded(scrollView: scrollView)
+ }
+
  private func scrollView(didEndScrolling scrollView: UIScrollView) {
  if self.autoScroller.restartsOnScrollEnd {
  self.autoScroller.restart()
@@ -270,6 +278,23 @@ extension PageboyViewController: UIPageViewControllerDelegate, UIScrollViewDeleg
  let pageOffset = (CGFloat(currentIndex) * pageSize) + (scrollOffset * indexDiff)
  return pageOffset / pageSize
  }
+
+ /// Update the scroll view contentOffset for bouncing preference if required.
+ ///
+ /// - Parameter scrollView: The scroll view.
+ /// - Returns: Whether the contentOffset was manipulated to achieve bouncing preference.
+ @discardableResult private func updateContentOffsetForBounceIfNeeded(scrollView: UIScrollView) -> Bool {
+ guard self.bounces == false else { return false }
+
+ let previousContentOffset = scrollView.contentOffset
+ if self.currentIndex == 0 && scrollView.contentOffset.x < scrollView.bounds.size.width {
+ scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0.0)
+ }
+ if self.currentIndex == (self.viewControllers?.count ?? 1) - 1 && scrollView.contentOffset.x > scrollView.bounds.size.width {
+ scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width, y: 0.0)
+ }
+ return previousContentOffset != scrollView.contentOffset
+ }
 }
 
 

Sources/Pageboy/PageboyViewController.swift

@@ -148,6 +148,9 @@ open class PageboyViewController: UIViewController {
  }
  }
 
+ /// default YES. if YES, bounces past edge of content and back again.
+ public var bounces: Bool = true
+
  /// Whether user interaction is enabled on the page view controller.
  ///
  /// Default is TRUE

Sources/PageboyTests/PageboyTransitionTests.swift

@@ -194,6 +194,17 @@ class PageboyTransitionTests: PageboyTests {
  }
  }
 
+ func testBouncingDisabledTransition() {
+ self.dataSource.numberOfPages = 2
+ self.pageboyViewController.dataSource = self.dataSource
+ self.pageboyViewController.bounces = false
+
+ self.simulateScroll(toPosition: -0.1)
+
+ XCTAssert(self.pageboyViewController.currentPosition!.x == 0.0,
+ "Bounces flag is not adhered to when setting contentOffset when false.")
+ }
+
  // MARK: Utils
 
  func simulateScroll(toPosition position: CGFloat) {