IOS圖像瀏覽器中迅速，編程

我試圖用使一個圖像瀏覽此toturial this toturial IOS圖像瀏覽器中迅速，編程

我想用「PagedScrollViewController」的例子，它使用迅速做出，我能夠在屏幕上顯示的圖像，但我有滾動問題。

滾動不是在頁面/照片之間停止，它自由滾動，因此loadVisiblePages總是被稱爲我滾動的每個像素。

可能我錯過了一些東西，你能幫助我嗎？這裏是我在做什麼：

謝謝

import UIKit 

class PagedScrollViewController:UIViewController,UIScrollViewDelegate { 


var pageImages:[UIImage] = [UIImage]() 
var pageViews:[UIView?] = [UIView]() 

var scrollView:UIScrollView = UIScrollView() 
var pageControl:UIPageControl = UIPageControl() 


func loadVisiblePages() { 
    // First, determine which page is currently visible 
    var pageWidth:CGFloat = self.scrollView.frame.size.width; 

    var page = Int(floor((self.scrollView.contentOffset.x * 2.0 + pageWidth)/(pageWidth * 2.0))); 

    // Update the page control 
    self.pageControl.currentPage = page; 

    // Work out which pages we want to load 
    var firstPage = page - 1; 
    var lastPage = page + 1; 

    // Purge anything before the first page 
    for (var i=0; i<firstPage; i++) { 
     println("1) purge index \(i)") 
     self.purgePage(i) 
    } 
    for (var i=firstPage; i<=lastPage; i++) { 
     println("2) load index \(i)") 
     self.loadPage(i) 
    } 
    for (var i = lastPage+1 ; i < self.pageImages.count ; i++) { 
     println("3) purge index \(i)") 
     self.purgePage(i) 
    } 
} 
// 
func loadPage(page:Int) { 
    if page < 0 || page >= self.pageImages.count { 
     // If it's outside the range of what we have to display, then do nothing 
     return; 
    } 

    // Load an individual page, first seeing if we've already loaded it 
    var pageView:UIView? = self.pageViews[page]; 
    if pageView == nil { 
     var frame:CGRect = self.scrollView.bounds; 
     //frame.origin.x = frame.size.width * CGFloat(page) 
     frame.origin.x = 320.0 * CGFloat(page) 
     frame.origin.y = 0.0 

     var newPageView:UIImageView = UIImageView(image: self.pageImages[page]) 
     newPageView.contentMode = UIViewContentMode.ScaleAspectFit; 
     newPageView.frame = frame; 
     self.scrollView.addSubview(newPageView) 
     self.pageViews[page] = newPageView 
    } 
} 

func purgePage(page:Int) { 
    if page < 0 || page >= self.pageImages.count { 
     // If it's outside the range of what we have to display, then do nothing 
     return; 
    } 

    // Remove a page from the scroll view and reset the container array 
    var pageView:UIView? = self.pageViews[page]; 
    if pageView != nil { 
     pageView?.removeFromSuperview() 
     self.pageViews[page] = UIView()//nil 
    } 
} 




override func viewDidLoad() { 
    super.viewDidLoad() 


    self.title = "Paged"; 

    self.view.backgroundColor = UIColor.blueColor() 

    // Set up the image we want to scroll & zoom and add it to the scroll view 
    self.pageImages.append(UIImage(named: "first.png")) 
    self.pageImages.append(UIImage(named: "second.png")) 
    self.pageImages.append(UIImage(named: "first.png")) 
    self.pageImages.append(UIImage(named: "second.png")) 
    self.pageImages.append(UIImage(named: "first.png")) 

    var pageCount = self.pageImages.count 

    self.scrollView.delegate = self 
    //self.tableView.showsHorizontalScrollIndicator = false 
    //self.tableView.showsVerticalScrollIndicator = false 

    // Set up the page control 
    self.pageControl.currentPage = 0; 
    self.pageControl.numberOfPages = pageCount; 

    self.pageControl.setTranslatesAutoresizingMaskIntoConstraints(false) 
    self.scrollView.setTranslatesAutoresizingMaskIntoConstraints(false) 

    self.view.addSubview(self.pageControl) 
    self.view.addSubview(self.scrollView) 


    //Set layout 
    var viewsDict = Dictionary <String, UIView>() 
    viewsDict["control"] = self.pageControl; 
    viewsDict["scrollView"] = self.scrollView; 

    self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[scrollView]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 
    self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[control]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 
    self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[scrollView(400)]-[control]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 


    // Set up the array to hold the views for each page 
    for (var i = 0; i < pageCount; ++i) { 
     self.pageViews.append(nil) 

    } 
} 


override func viewDidAppear(animated:Bool) { 
    super.viewDidAppear(animated) 

    // Set up the content size of the scroll view 
    var pagesScrollViewSize:CGSize = self.scrollView.frame.size; 
    self.scrollView.contentSize = CGSizeMake(pagesScrollViewSize.width * CGFloat(self.pageImages.count), pagesScrollViewSize.height); 

    // Load the initial set of pages that are on screen 
    self.loadVisiblePages() 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 

    //  self.scrollView = nil 
    //  self.pageControl = nil 
    //  self.pageImages = nil 
    //  self.pageViews = nil 
} 

func scrollViewDidScroll(scrollView:UIScrollView) { 
    // Load the pages which are now on screen 
    self.loadVisiblePages() 
    println("scrollViewDidScroll") 
} 



}

來源

2014-09-02 shay te

我是新來這。經過長時間的挖掘，我發現「self.scrollView.pagingEnabled = true」:) – 2014-09-02 23:14:56

的問題是我沒有把「self.scrollView.pagingEnabled」爲真。我現在仍然是UIKit。任何方式我做了一些性能改進，而且佈局通話只有現在需要的時候，希望有人會覺得這usfull :) 感謝http://www.raywenderlich.com

import UIKit 

class PagedScrollViewController:UIViewController,UIScrollViewDelegate { 

    var pageImages:[UIImage] = [UIImage]() 
    var pageViews:[UIView?] = [UIView]() 

    var scrollView:UIScrollView = UIScrollView() 
    var pageControl:UIPageControl = UIPageControl() 

    var viewingPage = -1 

    func loadVisiblePages() { 
     // First, determine which page is currently visible 
     var pageWidth:CGFloat = self.scrollView.frame.size.width; 
     var page = Int(floor((self.scrollView.contentOffset.x * 2.0 + pageWidth)/(pageWidth * 2.0))); 

     /* 
      Check that page have changed, 
      in case that user drag left in first page, or drag right in last page 
      a 'scrollViewDidEndDecelerating' is fired 
     */ 
     if viewingPage != page { 

      // Update the page control 
      self.pageControl.currentPage = page; 

      // Work out which pages we want to load 
      var firstPage = page - 1; 
      var lastPage = page + 1; 

      // Purge anything before the first page 
      for (var i=0; i<firstPage; i++) { 
       self.purgePage(i) 
      } 
      for (var i=firstPage; i<=lastPage; i++) { 
       self.loadPage(i) 
      } 
      for (var i = lastPage+1 ; i < self.pageImages.count ; i++) { 
       self.purgePage(i) 
      } 

      viewingPage = page 
     } 

    } 

    func loadPage(page:Int) { 
     if page < 0 || page >= self.pageImages.count { 
      // If it's outside the range of what we have to display, then do nothing 
      return; 
     } 

     // Load an individual page, first seeing if we've already loaded it 
     var pageView:UIView? = self.pageViews[page]; 
     if pageView == nil { 
      var frame:CGRect = self.scrollView.bounds; 
      //frame.origin.x = frame.size.width * CGFloat(page) 
      frame.origin.x = 320.0 * CGFloat(page) 
      frame.origin.y = 0.0 

      var newPageView:UIImageView = UIImageView(image: self.pageImages[page]) 
      newPageView.contentMode = UIViewContentMode.ScaleAspectFit; 
      newPageView.frame = frame; 
      self.scrollView.addSubview(newPageView) 
      self.pageViews[page] = newPageView 
     } 
    } 

    func purgePage(page:Int) { 
     if page < 0 || page >= self.pageImages.count { 
      // If it's outside the range of what we have to display, then do nothing 
      return; 
     } 

     // Remove a page from the scroll view and reset the container array 
     var pageView:UIView? = self.pageViews[page]; 
     if pageView != nil { 
      pageView?.removeFromSuperview() 
      self.pageViews[page] = nil 
     } 
    } 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     self.title = "Image viewer"; 

     self.view.backgroundColor = UIColor.blueColor() 

     // Set up the image we want to scroll & zoom and add it to the scroll view 
     self.pageImages.append(UIImage(named: "message_full.png")) 
     self.pageImages.append(UIImage(named: "heart_full")) 
     self.pageImages.append(UIImage(named: "star_full.png")) 
     self.pageImages.append(UIImage(named: "second.png")) 
     self.pageImages.append(UIImage(named: "first.png")) 

     var pageCount = self.pageImages.count 

     self.scrollView.pagingEnabled = true 
     self.scrollView.delegate = self 
     self.scrollView.showsHorizontalScrollIndicator = false 
     self.scrollView.showsVerticalScrollIndicator = false 

     // Set up the page control 
     self.pageControl.currentPage = 0; 
     self.pageControl.numberOfPages = pageCount; 

     self.pageControl.setTranslatesAutoresizingMaskIntoConstraints(false) 
     self.scrollView.setTranslatesAutoresizingMaskIntoConstraints(false) 

     self.view.addSubview(self.pageControl) 
     self.view.addSubview(self.scrollView) 


     //Set layout 
     var viewsDict = Dictionary <String, UIView>() 
     viewsDict["control"] = self.pageControl; 
     viewsDict["scrollView"] = self.scrollView; 

     self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[scrollView]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 
     self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[control]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 
     self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[scrollView(400)]-[control]-0-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)) 

     // Set up the array to hold the views for each page 
     for (var i = 0; i < pageCount; ++i) { 
      self.pageViews.append(nil) 
     } 
    } 


    override func viewDidAppear(animated:Bool) { 
     super.viewDidAppear(animated) 

     // Set up the content size of the scroll view 
     var pagesScrollViewSize:CGSize = self.scrollView.frame.size; 
     self.scrollView.contentSize = CGSizeMake(pagesScrollViewSize.width * CGFloat(self.pageImages.count), pagesScrollViewSize.height); 

     // Load the initial set of pages that are on screen 
     self.loadVisiblePages() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     //TODO make cleaning 
     //  self.scrollView = nil 
     //  self.pageControl = nil 
     //  self.pageImages = nil 
     //  self.pageViews = nil 
    } 


    func scrollViewDidEndDecelerating(scrollView: UIScrollView!) { 
     self.loadVisiblePages() 
    } 

}

來源

2014-09-02 23:34:41

IOS圖像瀏覽器中迅速，編程

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