向滚动视图添加可滚动按钮

Question

我想在滚动视图中滚动五个按钮。当用户停止拖动按钮时，它应该移动到下一个按钮。我在这里做错了什么？

class ViewController: UIViewController {

    @IBOutlet weak var categoryScrollView: UIScrollView!
    var categoryArr = ["Jack","Mark","Down","Bill","Steve"]

    override func viewDidLoad() {
        super.viewDidLoad()
        let scrollingView = colorButtonsView(CGSizeMake(150,categoryScrollView.frame.size.height), buttonCount: 5)
        categoryScrollView.contentSize = scrollingView.frame.size
        categoryScrollView.addSubview(scrollingView)
        categoryScrollView.showsVerticalScrollIndicator = false
        categoryScrollView.delegate = self
        categoryScrollView.pagingEnabled = true
        categoryScrollView.indicatorStyle = .Default
    }


func colorButtonsView(buttonSize:CGSize, buttonCount:Int) -> UIView {
        let buttonView = UIView()
        buttonView.frame.origin = CGPointMake(0,0)
        let padding = CGSizeMake(10, 10)
        buttonView.frame.size.width = (buttonSize.width + padding.width) * CGFloat(buttonCount)
        var buttonPosition = CGPointMake(padding.width * 0.5, padding.height)
        let buttonIncrement = buttonSize.width + padding.width
        for i in 0...(buttonCount - 1)  {
            var button = UIButton.buttonWithType(.Custom) as! UIButton
            button.frame.size = buttonSize
            button.frame.origin = buttonPosition
            buttonPosition.x = buttonPosition.x + buttonIncrement
            button.setTitle(categoryArr[i], forState: UIControlState.Normal)
            buttonView.addSubview(button)
        }
        return buttonView
    }
}
extension ViewController:UIScrollViewDelegate{
    func scrollViewDidEndDecelerating(scrollView: UIScrollView) {

        let index = round(scrollView.contentOffset.x / scrollView.frame.size.width)
        print(index)
    }
}

滚动视图滚动良好.. 但只有两次。它不会滚动到下一个按钮。我该怎么办？

Answer 1

func setContentOffset(scrollView: UIScrollView) {
    
    let numOfItems = itemCount  // 5
    let stopOver = scrollView.contentSize.width / CGFloat(numOfItems)
    let x = round(scrollView.contentOffset.x / stopOver) * stopOver
    
    guard x >= 0 && x <= scrollView.contentSize.width - scrollView.frame.width else {
        return
    }
    
    scrollView.setContentOffset(CGPointMake(x, scrollView.contentOffset.y), animated: true)
}

---

extension ViewController: UIScrollViewDelegate {

    func scrollViewWillBeginDecelerating(scrollView: UIScrollView) {
    
        setContentOffset(scrollView)
    }

    func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
    
        guard !decelerate else {
            return
        }
    
        setContentOffset(scrollView)
    }
}

还在 Github 做了一个演示项目
https://github.com/rishi420/ScrollViewCustomPaging

---

更新：

尝试考虑用户 endDragging 时的滚动速度。

var velocityX = CGFloat(0.0) 

.

func setContentOffset(scrollView: UIScrollView) {
    
    let numOfItems = itemCount
    let stopOver = scrollView.contentSize.width / CGFloat(numOfItems)
    var x = round((scrollView.contentOffset.x + (velocityX * 150)) / stopOver) * stopOver // 150 is for test. Change it for your liking
    
    x = max(0, min(x, scrollView.contentSize.width - scrollView.frame.width))
    
    scrollView.setContentOffset(CGPointMake(x, scrollView.contentOffset.y), animated: true)
}

.

func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>)
{
    velocityX = velocity.x
}

Answer 2

您是否尝试过使用 UITableView 而不是 UIScrollView 并使 tableview 的大小等于您想要的按钮大小。 然后将按钮添加到其单元格。 启用 UITableView 的 "Paging"

这将帮助您更好地管理内容，即更方便地管理按钮，因为您可以将按钮数组传递给 tableview 并在其 cellForAtIndex 方法中进行管理。

Answer 3

在您的scrollViewDidEndDecelerating() 方法中计算按钮索引后，只需调用scrollRectToVisible(rect, animated:) 并使用该索引处的按钮框架。

Answer 4

UIScrollView 并不总是减速。您可以使用此答案中的方法：https://stackoverflow.com/a/13067444，或使用scrollViewWillEndDragging:withVelocity:targetContentOffset: 方法中的targetContentOffset。

Answer 5

稍微微调了 Aruna 的代码。设置一些背景颜色，方便调试查看是否得到了预期的行为。

class ViewController: UIViewController {

    @IBOutlet weak var categoryScrollView: UIScrollView!
    var categoryArr = ["Jack","Mark","Down","Bill","Steve"]
    var buttonColors = [UIColor.greenColor(), UIColor.blueColor(), UIColor.blackColor(), UIColor.cyanColor(), UIColor.magentaColor()]
    let kPadding:CGFloat = 10

    override func viewDidLoad() {
        super.viewDidLoad()

        let buttonSize = CGSizeMake(categoryScrollView.bounds.size.width/2, categoryScrollView.bounds.size.height/2)//hal

        let scrollingView = colorButtonsView(buttonSize, buttonCount: 5)
        categoryScrollView.contentSize = scrollingView.frame.size
        categoryScrollView.addSubview(scrollingView)
        categoryScrollView.showsVerticalScrollIndicator = false
        categoryScrollView.delegate = self
        categoryScrollView.pagingEnabled = true
        categoryScrollView.indicatorStyle = .Default
        categoryScrollView.contentOffset = CGPointMake(0, 0)
    }


    func colorButtonsView(buttonSize:CGSize, buttonCount:Int) -> UIView {
        let buttonView = UIView()
        buttonView.frame.origin = CGPointMake(0,0)
        let padding = CGSizeMake(kPadding, kPadding)
        buttonView.frame.size.width = (buttonSize.width + padding.width) * CGFloat(buttonCount)
        var buttonPosition = CGPointMake(0, padding.height)
        let buttonIncrement = buttonSize.width + padding.width
        for i in 0...(buttonCount - 1)  {
            let button = UIButton(type: .Custom)
            button.frame.size = buttonSize
            button.frame.origin = buttonPosition
            buttonPosition.x = buttonPosition.x + buttonIncrement
            button.setTitle(categoryArr[i], forState: UIControlState.Normal)
            button.backgroundColor = buttonColors[i]
            buttonView.addSubview(button)
        }
        buttonView.backgroundColor = UIColor.redColor()
        return buttonView
    }
}
extension ViewController:UIScrollViewDelegate{
    func scrollViewDidEndDecelerating(scrollView: UIScrollView) {

        let index = round(scrollView.contentOffset.x / scrollView.frame.size.width)
        print(index)
    }
}

Answer 6

请检查修改后的代码：

class ViewController: UIViewController {

@IBOutlet weak var categoryScrollView: UIScrollView!
var categoryArr = ["Jack","Mark","Down","Bill","Steve"]

override func viewDidLoad() {
    super.viewDidLoad()
    let scrollingView = colorButtonsView(CGSizeMake(categoryScrollView.frame.size.width / 3 ,categoryScrollView.frame.size.height), buttonCount: 5)
    categoryScrollView.contentSize = scrollingView.frame.size
    categoryScrollView.addSubview(scrollingView)
    categoryScrollView.showsVerticalScrollIndicator = false
    categoryScrollView.delegate = self
    categoryScrollView.pagingEnabled = false
    categoryScrollView.bounces = false
    categoryScrollView.indicatorStyle = .Default
}


func colorButtonsView(buttonSize:CGSize, buttonCount:Int) -> UIView {
    let buttonView = UIView()
    buttonView.frame.origin = CGPointMake(0,0)
    let padding = CGSizeMake(10, 10)
    buttonView.frame.size.width = (buttonSize.width + padding.width) * CGFloat(buttonCount)
    var buttonPosition = CGPointMake(padding.width * 0.5, padding.height)
    let buttonIncrement = buttonSize.width + padding.width
    for i in 0...(buttonCount - 1)  {
        let button = UIButton(type: .Custom)
        button.backgroundColor = UIColor.redColor()
        button.frame.size = buttonSize
        button.frame.origin = buttonPosition
        buttonPosition.x = buttonPosition.x + buttonIncrement
        button.setTitle(categoryArr[i], forState: UIControlState.Normal)
        buttonView.addSubview(button)
    }
    return buttonView
}

}

extension ViewController:UIScrollViewDelegate{

    func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        let buttonWidth = scrollView.frame.size.width / 3
        let index = round(scrollView.contentOffset.x / buttonWidth)
        targetContentOffset.memory.x = index*buttonWidth + index*10
    }

}