我最初的UIScrollView问题现在似乎与autolayout有关 [英] my initial problems with UIScrollView now appear to be related to autolayout
问题描述
对于我使用 UIScrollView 的第一次挑战我修改了
ViewController.swift（已更正）
import UIKit
class ViewController：UIViewController，UIScrollViewDelegate {
let scrollView = UIScrollView（frame： CGRect（x：0，y：0，宽度：320，高度：480））
var views = [UIView]（）
var lables = [UILabel]（）
var colors：[UIColor] = [UIColor.red，UIColor.magenta，UIColor.blue，UIColor.cyan，UIColor.green，UIColor.yellow]
var frame：CGRect = CGRect.zero
var pageControl：UIPageControl = UIPageControl（frame：CGRect（x：50，y：500，width：200，height：50））
覆盖func viewDidLoad（）{
super.viewDidLoad（）
initialiseViewsAndLables（）
configurePageControl（）
scrollView.delegate = self
self.view.addSubview（scrollView）
for index in 0 ..< colors.count {
frame.origin.x = self.scrollView.frame.size。 width * CGFloat（index）
frame.size = self.scrollView.frame.size
self.scrollView.isPagingEnabled = true
views [index] .frame = frame
views [index] .backgroundColor = colors [Int（index）]
views [index] .layer.cornerRadius = 20
views [index] .layer.masksToBounds = true
lables [index] .frame = frame
lables [index] .center = CGPoint（x：（view.frame.midX + frame.origin.x），y：view.frame.midY）
lables [index] .text = String（index + 1）
lables [index] .defaultFont = UIFont（name：HelveticaNeue，size：CGFloat（200））
lables [index] .textAlignment = .center
lables [index] .textColor = .black
let subView1 = views [index]
let subView2 = lables [index]
self.scrollView .addSubview（subView1）
self.scrollView .addSubview（subView2）
}
print（views，lables）
self.scrollView.contentSize = CGSize（width：self.scrollView.frame.size.width * CGFloat（colors.count）， height：self.scrollView.frame.size.height）
pageControl.addTarget（self，action：Selector（（changePage：）），for：UIControlEvents.valueChanged）
}
func initialiseViewsAndLables（）{
//视图大小[]和标签[]链接到可用颜色
索引为0 ..< colors.count {
views.insert（UIView（），at：index）
lables.insert（UILabel（），at：index）
}
}
func configurePageControl （）{
//可用页面总数基于可用颜色
self.pageControl.numberOfPages = colors.count
self.pageControl.currentPage = 0
self.pageControl.backgroundColor = getColour（）
self.pageControl.pageIndicatorTintColor = UIColor.black
self.pageControl.currentPageIndicatorTintColor = UIColor.green
self.view.addSubview（pageControl）
}
func getColour（） - > UIColor {
let index = colors [pageControl.currentPage]
return（index）
}
func changePage（sender：AnyObject） - > （）{
scrollView.setContentOffset（CGPoint（x：CGFloat（pageControl.currentPage）* scrollView.frame.size.width，y：0），animated：true）
}
func scrollViewDidEndDecelerating（_ scrollView：UIScrollView）{
let pageNumber = round（scrollView.contentOffset.x / scrollView.frame.size.width）
pageControl.currentPage = Int（pageNumber）
pageControl.backgroundColor = getColour（）
}
}
扩展程序
扩展名UILabel {
var defaultFont：UIFont？ {
get {return self.font}
set {self.font = newValue}
}
}
每帧上标签的中心点必须由内容视图的原点偏移（正如Baglan指出的那样） ）。我相应地修改了以下代码行。
lables [Int（index）]。center = CGPoint（x :( view.frame.midX + frame.origin.x），y：view.frame.midY）
For my first challenge using UIScrollView I modified this example to make UIScrollView display not just another background colour but another UIView and UILabel on each page. But I could have just as easily chosen to display objects like UITableView, UIButton or UIImage.
Potentially, UIScrollView could be much more than a giant content view where users scroll from one part to the next, e.g., some pages might have a UIButton that takes a user to a specific page, the same way we use books.
Code Improvements
My question has evolved since I first posted it. Initially the labels piled up on page 1 (as shown below) but this has now been corrected. I also included this extension to make the font larger.
Further improvement ?
As the code evolved I became more aware of other issues e.g. iPhone 5 images (below) appear differently on iPhone 7 where the UILabel is centred but not the UIView. So my next challenge is possibly to learn how to combine UIScrollView with Autolayout. I invite anyone to spot other things that might be wrong.
ViewController.swift (corrected)
import UIKit
class ViewController: UIViewController,UIScrollViewDelegate {
let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: 320, height: 480))
var views = [UIView]()
var lables = [UILabel]()
var colors:[UIColor] = [UIColor.red, UIColor.magenta, UIColor.blue, UIColor.cyan, UIColor.green, UIColor.yellow]
var frame: CGRect = CGRect.zero
var pageControl: UIPageControl = UIPageControl(frame: CGRect(x: 50, y: 500, width: 200, height: 50))
override func viewDidLoad() {
super.viewDidLoad()
initialiseViewsAndLables()
configurePageControl()
scrollView.delegate = self
self.view.addSubview(scrollView)
for index in 0..<colors.count {
frame.origin.x = self.scrollView.frame.size.width * CGFloat(index)
frame.size = self.scrollView.frame.size
self.scrollView.isPagingEnabled = true
views[index].frame = frame
views[index].backgroundColor = colors[Int(index)]
views[index].layer.cornerRadius = 20
views[index].layer.masksToBounds = true
lables[index].frame = frame
lables[index].center = CGPoint(x: (view.frame.midX + frame.origin.x), y: view.frame.midY)
lables[index].text = String(index + 1)
lables[index].defaultFont = UIFont(name: "HelveticaNeue", size: CGFloat(200))
lables[index].textAlignment = .center
lables[index].textColor = .black
let subView1 = views[index]
let subView2 = lables[index]
self.scrollView .addSubview(subView1)
self.scrollView .addSubview(subView2)
}
print(views, lables)
self.scrollView.contentSize = CGSize(width: self.scrollView.frame.size.width * CGFloat(colors.count), height: self.scrollView.frame.size.height)
pageControl.addTarget(self, action: Selector(("changePage:")), for: UIControlEvents.valueChanged)
}
func initialiseViewsAndLables() {
// Size of views[] and lables[] is linked to available colors
for index in 0..<colors.count {
views.insert(UIView(), at:index)
lables.insert(UILabel(), at: index)
}
}
func configurePageControl() {
// Total number of available pages is based on available colors
self.pageControl.numberOfPages = colors.count
self.pageControl.currentPage = 0
self.pageControl.backgroundColor = getColour()
self.pageControl.pageIndicatorTintColor = UIColor.black
self.pageControl.currentPageIndicatorTintColor = UIColor.green
self.view.addSubview(pageControl)
}
func getColour() -> UIColor {
let index = colors[pageControl.currentPage]
return (index)
}
func changePage(sender: AnyObject) -> () {
scrollView.setContentOffset(CGPoint(x: CGFloat(pageControl.currentPage) * scrollView.frame.size.width, y: 0), animated: true)
}
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
pageControl.currentPage = Int(pageNumber)
pageControl.backgroundColor = getColour()
}
}
Extension
extension UILabel{
var defaultFont: UIFont? {
get { return self.font }
set { self.font = newValue }
}
}
The centre point of the lable on each frame must be offset by the origin of the content view (as Baglan pointed out). I've modified the following line of code accordingly.
lables[Int(index)].center = CGPoint(x: (view.frame.midX + frame.origin.x), y: view.frame.midY)
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