我正在尝试创建像Flipkart一样的水平滑块。我正在使用带有水平滚动和分页的collectionView。单元格包含imageView。我成功地手动水平滚动项目，但我希望所有这些项目都自动和手动移动。我没有得到如何自动滚动collectionView的项目。请指导我这样做。
我在viewDidAppear中使用了这段代码：
let visibleIndexPath: NSIndexPath = self.collectionView.indexPathForCell(cell)!
self.collectionView.scrollToItemAtIndexPath(visibleIndexPath,
atScrollPosition: UICollectionViewScrollPosition.CenteredHorizontally, animated: true)
谢谢。
编辑：
import UIKit
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
@IBOutlet var pageControl: UIPageControl!
@IBOutlet var collectionView: UICollectionView!
var begin = false
let image1 = UIImage(named: "Slide 1")
let image2 = UIImage(named: "Slide 2")
let image3 = UIImage(named: "Slide 1")
var images = [UIImage]()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
images = [image1!, image2!, image3!]
startTimer()
}
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
pageControl.numberOfPages = images.count
return images.count
}
var cell : CollectionViewCell1!
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
cell = collectionView.dequeueReusableCellWithReuseIdentifier("CollectionViewCell1", forIndexPath: indexPath) as! CollectionViewCell1
cell.cell_image.image = images[indexPath.row]
return cell
}
/**
Scroll to Next Cell
*/
func scrollToNextCell(){
//get cell size
let cellSize = CGSizeMake(self.view.frame.width, self.view.frame.height);
//get current content Offset of the Collection view
let contentOffset = collectionView.contentOffset;
//scroll to next cell
if begin == true
{
pageControl.currentPage == 0
collectionView.scrollRectToVisible(CGRectZero, animated: true)
begin = false
}
else
{
collectionView.scrollRectToVisible(CGRectMake(contentOffset.x + cellSize.width, contentOffset.y, cellSize.width, cellSize.height), animated: true);
}
}
/**
Invokes Timer to start Automatic Animation with repeat enabled
*/
func startTimer() {
NSTimer.scheduledTimerWithTimeInterval(2.0, target: self, selector: #selector(ViewController.scrollToNextCell), userInfo: nil, repeats: true);
}
func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
// If the scroll animation ended, update the page control to reflect the current page we are on
pageControl.currentPage = Int((collectionView.contentOffset.x / collectionView.contentSize.width) * CGFloat(images.count))
if collectionView.contentSize.width == collectionView.contentOffset.x + self.view.frame.width
{
begin = true
}
}
func scrollViewDidEndScrollingAnimation(scrollView: UIScrollView) {
// Called when manually setting contentOffset
scrollViewDidEndDecelerating(scrollView)
}
}
这是我的全部代码..我无法在最后一个单元格后进入第一个单元格。请帮我。
以下是您可以尝试的代码：
/**
Scroll to Next Cell
*/
func scrollToNextCell(){
//get Collection View Instance
let collectionView:UICollectionView;
//get cell size
let cellSize = CGSizeMake(self.view.frame.width, self.view.frame.height);
//get current content Offset of the Collection view
let contentOffset = collectionView.contentOffset;
//scroll to next cell
collectionView.scrollRectToVisible(CGRectMake(contentOffset.x + cellSize.width, contentOffset.y, cellSize.width, cellSize.height), animated: true);
}
/**
Invokes Timer to start Automatic Animation with repeat enabled
*/
func startTimer() {
let timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("scrollToNextCell"), userInfo: nil, repeats: true);
}
/**
Scroll to Next Cell
*/
func scrollToNextCell(){
//get cell size
let cellSize = CGSizeMake(self.view.frame.width, self.view.frame.height);
//get current content Offset of the Collection view
let contentOffset = collectionView.contentOffset;
if collectionView.contentSize.width <= collectionView.contentOffset.x + cellSize.width
{
collectionView.scrollRectToVisible(CGRectMake(0, contentOffset.y, cellSize.width, cellSize.height), animated: true);
} else {
collectionView.scrollRectToVisible(CGRectMake(contentOffset.x + cellSize.width, contentOffset.y, cellSize.width, cellSize.height), animated: true);
}
}
/**
Invokes Timer to start Automatic Animation with repeat enabled
*/
func startTimer() {
NSTimer.scheduledTimerWithTimeInterval(2.0, target: self, selector: Selector("scrollToNextCell"), userInfo: nil, repeats: true);
}
斯威夫特3
此测试代码滚动到下一个单元格并返回到最后一个单元格后的第一个项目。
func setTimer() {
let _ = Timer.scheduledTimer(timeInterval: 3.0, target: self, selector: #selector(MainVC.autoScroll), userInfo: nil, repeats: true)
}
var x = 1
@objc func autoScroll() {
if self.x < self.storiesForCollectionView.count {
let indexPath = IndexPath(item: x, section: 0)
self.collectionViewUp.scrollToItem(at: indexPath, at: .centeredHorizontally, animated: true)
self.x = self.x + 1
} else {
self.x = 0
self.collectionViewUp.scrollToItem(at: IndexPath(item: 0, section: 0), at: .centeredHorizontally, animated: true)
}
}
override func viewDidLoad() {
super.viewDidLoad()
setTimer()
}
对于Swift4
override func viewDidLoad() {
super.viewDidLoad()
startTimer()
}
func startTimer() {
let timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(self.scrollAutomatically), userInfo: nil, repeats: true)
}
@objc func scrollAutomatically(_ timer1: Timer) {
if let coll = topMenuCollection {
for cell in coll.visibleCells {
let indexPath: IndexPath? = coll.indexPath(for: cell)
if ((indexPath?.row)! < < banner.count - 1){
let indexPath1: IndexPath?
indexPath1 = IndexPath.init(row: (indexPath?.row)! + 1, section: (indexPath?.section)!)
coll.scrollToItem(at: indexPath1!, at: .right, animated: true)
}
else{
let indexPath1: IndexPath?
indexPath1 = IndexPath.init(row: 0, section: (indexPath?.section)!)
coll.scrollToItem(at: indexPath1!, at: .left, animated: true)
}
}
}
}
topMenuCollection： - 您的集合视图
banner.Count： - 包含集合视图的多个单元格
我建议使用集合视图方法scrollToItem(at:at:animated:)而不是scrollRectToVisible。它使您无需进行计算以确定要显示的矩形。您只需指定要滚动的indexPath即可。
迅捷4：
func scrollToNextCell(){
//get cell size
let cellSize = view.frame.size
//get current content Offset of the Collection view
let contentOffset = collectionView.contentOffset
if collectionView.contentSize.width <= collectionView.contentOffset.x + cellSize.width
{
let r = CGRect(x: 0, y: contentOffset.y, width: cellSize.width, height: cellSize.height)
collectionView.scrollRectToVisible(r, animated: true)
} else {
let r = CGRect(x: contentOffset.x + cellSize.width, y: contentOffset.y, width: cellSize.width, height: cellSize.height)
collectionView.scrollRectToVisible(r, animated: true);
}
}
这是我稍微改进的解决方案。当用户手动开始滚动时，它会停止滚动，如果再次重复使用该单元，则会重新启动滚动。
var x = 0
weak var timer: Timer?
var cashbackOffers = [CashbackOffer]() {
didSet {
collectionView.reloadData()
autoScroll()
}
}
fileprivate func autoScroll() {
x = 0
timer?.invalidate()
timer = Timer.scheduledTimer(withTimeInterval: 3.0, repeats: true) { [weak self] timer in
guard let `self` = self else {
timer.invalidate()
return
}
if self.cashbackOffers.count == 0 {
return
}
if self.x < self.cashbackOffers.count {
let indexPath = IndexPath(item: self.x, section: 0)
self.collectionView.scrollToItem(at: indexPath, at: .centeredHorizontally, animated: true)
self.x = self.x + 1
} else {
self.x = 1
self.collectionView.scrollToItem(at: IndexPath(item: 0, section: 0), at: .centeredHorizontally, animated: true)
}
}
timer?.fire()
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.isTracking {
timer?.invalidate()
}
}
override func awakeFromNib() {
super.awakeFromNib()
autoScroll()
}
/**
Scroll to Next Cell
*/
@objc func scrollToNextCell(){
//get cell size
let cellSize = CGSize(width:self.view.frame.size.width, height:viewForCV.frame.size.height)
//get current content Offset of the Collection view
let contentOffset = cvAdvertisements.contentOffset;
if cvAdvertisements.contentSize.width <= cvAdvertisements.contentOffset.x + cellSize.width
{
cvAdvertisements.scrollRectToVisible(CGRect(x:0, y:contentOffset.y, width:cellSize.width, height:cellSize.height), animated: true);
} else {
cvAdvertisements.scrollRectToVisible(CGRect(x:contentOffset.x + cellSize.width, y:contentOffset.y, width:cellSize.width, height:cellSize.height), animated: true);
}
}
/**
Invokes Timer to start Automatic Animation with repeat enabled
*/
func startTimer() {
Timer.scheduledTimer(timeInterval: 2.0, target: self, selector: #selector(LoginViewController.scrollToNextCell), userInfo: nil, repeats: true);
}
试试这个
var index = 0
var inForwardDirection = true
var timer: Timer?
@objc func scrollToNextCell() {
//scroll to next cell
let items = collectionViewTable.numberOfItems(inSection: 0)
if (items - 1) == index {
collectionViewTable.scrollToItem(at: IndexPath(row: index, section: 0), at: UICollectionViewScrollPosition.right, animated: true)
} else if index == 0 {
collectionViewTable.scrollToItem(at: IndexPath(row: index, section: 0), at: UICollectionViewScrollPosition.left, animated: true)
} else {
collectionViewTable.scrollToItem(at: IndexPath(row: index, section: 0), at: UICollectionViewScrollPosition.centeredHorizontally, animated: true)
}
if inForwardDirection {
if index == (items - 1) {
index -= 1
inForwardDirection = false
} else {
index += 1
}
} else {
if index == 0 {
index += 1
inForwardDirection = true
} else {
index -= 1
}
}
}
/**
call this method when collection view loaded
*/
func startTimer() {
if timer == nil {
timer = Timer.scheduledTimer(timeInterval: 5.0, target: self, selector: #selector(scrollToNextCell), userInfo: nil, repeats: true);
}
}