在图像幻灯片和页面控制中添加 NSTimer 以自动移动图像

Question

这是手动拖动时图像滑块工作正常，图像随着页面控制指示器的变化而变化，但我想将计时器添加到以下代码中并自动移动图像和指示器。请帮助我在此代码中应用 NS 计时器，并且还想从最后一个图像移动到第一个图像，依此类推。

@implementation DashboardViewController {
NSArray * animationArray;
}
@synthesize scroller = scroller;
@synthesize pageControl = pageControl;


-(void) viewDidLoad {
[super viewDidLoad];
scroller.pagingEnabled = YES;
scroller.showsHorizontalScrollIndicator = NO;
scroller.delegate = self;

animationArray = [NSArray arrayWithObjects: [UIImage imageNamed: @ "image1.jpg"],
[UIImage imageNamed: @ "image2.jpg"],
[UIImage imageNamed: @ "image3.jpg"],
[UIImage imageNamed: @ "image4.png"],
[UIImage imageNamed: @ "image5.jpg"],
nil
];

CGRect scrollFrame = CGRectMake(0, 0, self.view.frame.size.width, self.scroller.frame.size.height);
scroller.frame = scrollFrame;

self.scroller.contentSize = CGSizeMake(self.scroller.frame.size.width * animationArray.count, self.scroller.frame.size.height);
for (int i = 0; i < animationArray.count; i++) {
CGRect frame;
frame.origin.x = self.scroller.frame.size.width * i;
frame.origin.y = 0;
frame.size = self.scroller.frame.size;
UIImageView * imgView = [
[UIImageView alloc] initWithFrame: CGRectMake(self.scroller.frame.size.width * i, 0, self.scroller.frame.size.width, self.scroller.frame.size.height)
];
imgView.image = [animationArray objectAtIndex: i];
imgView.frame = frame;

[self.scroller addSubview: imgView];
}
self.pageControl.currentPage = 0;
}

-(void) scrollViewDidScroll: (UIScrollView * ) sender {
if (!pageControlBeingUsed) {
// Switch the indicator when more than 50% of the previous/next page is visible
CGFloat pageWidth = self.scroller.frame.size.width;
int page = floor((self.scroller.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
self.pageControl.currentPage = page;
}
}
-(void) scrollViewWillBeginDragging: (UIScrollView * ) scrollView {
pageControlBeingUsed = NO;
}
-(void) scrollViewDidEndDecelerating: (UIScrollView * ) scrollView {
[self setIndiactorForCurrentPage];
}

-(void) setIndiactorForCurrentPage {
uint page = scroller.contentOffset.x / scroller.frame.size.width;
[pageControl setCurrentPage: page];

}

- (IBAction) changePage {
// Update the scroll view to the appropriate page
CGRect frame;
pageControl.currentPage = animationArray.count;
frame.origin.x = self.scroller.frame.size.width * self.pageControl.currentPage;
frame.origin.y = 0;
frame.size = self.scroller.frame.size;
[self.scroller scrollRectToVisible: frame animated: YES];
pageControlBeingUsed = YES;

}

- (void) didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
self.scroller = nil;
self.pageControl = nil;
}

Answer 1

请尝试此代码用于 NSTimer (我使用 collectionView 以方便使用(

var timer : Timer?
var currentFeaturedCouponIndex = 0
//MARK: - NSTimer -
func setupTimer(){
timer = Timer.scheduledTimer(timeInterval: 5.0, target: self, selector: #selector(self.scrollFeatured), userInfo: nil, repeats: true);
}
func scrollFeatured(){
if self.arrFeaturedCoupon.count > 0 {
//Becauese we scroll coupon if total is > 1
if self.arrFeaturedCoupon.count > 1 {
if self.currentFeaturedCouponIndex < self.arrFeaturedCoupon.count - 1 {
self.currentFeaturedCouponIndex = self.currentFeaturedCouponIndex + 1
}
else {
self.currentFeaturedCouponIndex = 0
}
self.pageControl.currentPage = currentFeaturedCouponIndex
//When currentFeaturedCouponIndex == 0  we make animated: false
if self.currentFeaturedCouponIndex == 0 {
self.featuredCouponColView.scrollToItem(at: self.featuredCouponCurrentIndexPath, at: UICollectionViewScrollPosition.left, animated: false)
}
else {
self.featuredCouponColView.scrollToItem(at: self.featuredCouponCurrentIndexPath, at: UICollectionViewScrollPosition.left, animated: true)
}
}
}
}

使计时器在所需的时间和地点失效

func invalidateTimer(){
if timer != nil {
self.timer!.invalidate()
self.timer = nil
}
}