ScrollView + PageControl不会滚动

Question

我有那段代码：

import UIKit

class ProjectsViewController: UIViewController, UIScrollViewDelegate {
  @IBOutlet weak var pageControlBookChapters: UIPageControl!
  @IBOutlet weak var scrollViewBookChapters: UIScrollView!
  @IBOutlet weak var contentsImageView: UIImageView!
  @IBOutlet weak var contentsTextLabel: UILabel!
  @IBOutlet weak var contentsLabel: UILabel!
  @IBOutlet weak var projectName: UILabel!
  @IBOutlet weak var projectImageView: UIImageView!

  var page = 0

  let arrImages : [String] = ["Captura1.jpg", "captura 2.jpg", "captura 3.jpg", "captura 4.jpg", "captura 5.jpg"];

  override func viewDidLoad() {
    super.viewDidLoad()
    self.createHelpView()
    pageControlBookChapters.backgroundColor = UIColor.clearColor()
    pageControlBookChapters.pageIndicatorTintColor = UIColor.lightGrayColor()
    pageControlBookChapters.currentPageIndicatorTintColor = UIColor(red: 251/255, green: 108/255, blue: 108/255, alpha: 1.0)
    pageControlBookChapters.tintAdjustmentMode = UIViewTintAdjustmentMode.Dimmed
    pageControlBookChapters.numberOfPages = arrImages.count
    pageControlBookChapters.currentPage = 0

    scrollViewBookChapters.scrollEnabled = true
    scrollViewBookChapters.alwaysBounceHorizontal = true
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
  }

  func createHelpView() {

    var x = 50
    for var i=0; i<arrImages.count; i++  {
      var imgView = UIImageView(frame: CGRectMake(CGFloat(x), 50, CGFloat(scrollViewBookChapters.frame.width-100), CGFloat(scrollViewBookChapters.frame.height-150)))
      imgView.autoresizingMask = UIViewAutoresizing.FlexibleBottomMargin
      imgView.backgroundColor = UIColor.clearColor()
      imgView.image = UIImage(named: arrImages[i])
      imgView.contentMode = UIViewContentMode.ScaleAspectFit
      scrollViewBookChapters.addSubview(imgView)

      x = x + Int(scrollViewBookChapters.frame.width)
    }
    scrollViewBookChapters.contentSize = CGSizeMake(CGFloat(arrImages.count)*self.view.frame.width, 0)
  }

  func scrollViewDidScroll(scrollView: UIScrollView) {
    var pageWidth = CGFloat(scrollViewBookChapters.frame.width)
    var fractionalPage = scrollViewBookChapters.contentOffset.x / pageWidth
    page = lround(CDouble(fractionalPage))
    pageControlBookChapters.currentPage = page
  }
}

这正确地创建了scrollview和页面控件的点，但是当我尝试滚动它时，它不会移动，只显示要滚动的行，但即使我点击点按钮它也没有做任何事情。有什么不对吗？我甚至宣布scrollEnabled并水平弹跳以强制它，但没有任何反应。 我已经检查了contentSize并且似​​乎正常工作。