我想在scrollview中滚动五个按钮.当用户停止拖动按钮时,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)
}
}
滚动浏览很好..但只有两次.它不滚动到下一个按钮.我该怎么办？
解决方法
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 https://github.com/rishi420/ScrollViewCustomPaging中做了一个演示项目
更新：
尝试在用户endDragging时考虑滚动速度.
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,animated: true)
}
.
func scrollViewWillEndDragging(scrollView: UIScrollView,withVelocity velocity: CGPoint,targetContentOffset: UnsafeMutablePointer<CGPoint>)
{
velocityX = velocity.x
}
