ios - Paging using UIScrollView -

i'm trying display multiple images using uiscrollview , page control, think screenshots of apps on app store. yet reason, uiscrollview not scrolling. checked, , uiscrollview's contentsize's width larger uiscrollview's width. might worth noting put page control in uiscrollview, displays on top of pictures. code follows:

import uikit  class itemdetailviewcontroller: uiviewcontroller, uiscrollviewdelegate {  @iboutlet weak var scrollview: uiscrollview! @iboutlet weak var pagecontrol: uipagecontrol!   var itemselected: item! var pageviews: [uiimageview?] = [] var pagecount: int!  override func viewdidload() {     super.viewdidload()      // additional setup after loading view.      pagecount = itemselected.images.count     pagecontrol.currentpage = 0     pagecontrol.numberofpages = pagecount      _ in 0..<pagecount {         pageviews.append(nil)     }      scrollview.frame.size = cgsizemake(view.frame.width, view.frame.height/2.0)     let pagesize = scrollview.frame.size     scrollview.contentsize = cgsizemake(pagesize.width * cgfloat(pagecount), pagesize.height)     loadvisiblepages()     scrollview.delegate = self }  override func didreceivememorywarning() {     super.didreceivememorywarning()     // dispose of resources can recreated. }  override func viewwillappear(animated: bool) {     super.viewwillappear(animated)     tabbarcontroller?.tabbar.hidden = true }  override func viewwilldisappear(animated: bool) {     super.viewdiddisappear(animated)     tabbarcontroller?.tabbar.hidden = false }   // mark: - helper functions  func loadpage(page: int){     if page < 0 || page >= pagecount {         // page outside of range, nothing         return     }      if let pageview = pageviews[page] {         // page loaded, nothing         return     } else {         var frame = scrollview.bounds         frame.origin.x = frame.size.width * cgfloat(page)         frame.origin.y = 0.0          let newpageview = uiimageview(image: itemselected.images[page])         newpageview.contentmode = .scaletofill         newpageview.frame = frame         scrollview.addsubview(newpageview)          pageviews[page] = newpageview     }   }  func purgepage(page: int){     if page < 0 || page >= pagecount {         // page outside of range, nothing         return     }      if let pageview = pageviews[page]{         pageview.removefromsuperview()         pageviews[page] = nil     } }  func loadvisiblepages(){     let pagewidth = scrollview.frame.size.width     let page = int(floor(scrollview.contentoffset.x * 2.0 + pagewidth)/(2.0 * pagewidth))      pagecontrol.currentpage = page      let firstpage = page - 1     let lastpage = page + 1      var index = 0; index < firstpage; index++ {         purgepage(index)     }      index in firstpage ... lastpage {         loadpage(index)     }      var index = lastpage + 1; index < itemselected.images.count; index++ {         purgepage(index)     } }  // mark: - scroll view delegate methods  func scrollviewdidscroll(scrollview: uiscrollview) {     loadvisiblepages() } } 

what causing issue?

better use uipageviewcontroller u want show images. u can see tutorial how there there