使用UIScrollView 结合 UIImageView 实现图片循环滚动
场景:
在开发工作中,有时我们需要实现一组图片循环滚动的情况。当我们使用 UIScrollView 结合 UIImageView 来实现时,一般 UIImageView 会尽量考虑重用,下面例子是以(左中右)三个 UIImageView 的使用,其实也可以考虑使用 两个 UIImageView 实现的情况。这样避免 一组图片多少个就对应多少个 UIImageView 所导致占用过多内存的情况。
效果如下:
ViewController.h
#import <uikit uikit.h=""> @interface ViewController : UIViewController <uiscrollviewdelegate> @property (strong, nonatomic) UIScrollView *scrV; @property (strong, nonatomic) UIPageControl *pageC; @property (strong, nonatomic) UIImageView *imgVLeft; @property (strong, nonatomic) UIImageView *imgVCenter; @property (strong, nonatomic) UIImageView *imgVRight; @property (strong, nonatomic) UILabel *lblImageDesc; @property (strong, nonatomic) NSMutableDictionary *mDicImageData; @property (assign, nonatomic) NSUInteger currentImageIndex; @property (assign, nonatomic) NSUInteger imageCount; @end</uiscrollviewdelegate></uikit>
ViewController.m
#import "ViewController.h" #define kWidthOfScreen [[UIScreen mainScreen] bounds].size.width #define kHeightOfScreen [[UIScreen mainScreen] bounds].size.height #define kImageViewCount 3 @interface ViewController () /** * 加载图片数据 */ - (void)loadImageData; /** * 添加滚动视图 */ - (void)addScrollView; /** * 添加三个图片视图到滚动视图内 */ - (void)addImageViewsToScrollView; /** * 添加分页控件 */ - (void)addPageControl; /** * 添加标签;用于图片描述 */ - (void)addLabel; /** * 根据当前图片索引设置信息 * * @param currentImageIndex 当前图片索引;即中间 */ - (void)setInfoByCurrentImageIndex:(NSUInteger)currentImageIndex; /** * 设置默认信息 */ - (void)setDefaultInfo; /** * 重新加载图片 */ - (void)reloadImage; - (void)layoutUI; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; [self layoutUI]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (void)loadImageData { NSString *path = [[NSBundle mainBundle] pathForResource:@"ImageInfo" ofType:@"plist"]; _mDicImageData = [NSMutableDictionary dictionaryWithContentsOfFile:path]; _imageCount = _mDicImageData.count; } - (void)addScrollView { _scrV = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; _scrV.contentSize = CGSizeMake(kWidthOfScreen * kImageViewCount, kHeightOfScreen); _scrV.contentOffset = CGPointMake(kWidthOfScreen, 0.0); _scrV.pagingEnabled = YES; _scrV.showsHorizontalScrollIndicator = NO; _scrV.delegate = self; [self.view addSubview:_scrV]; } - (void)addImageViewsToScrollView { //图片视图;左边 _imgVLeft = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, kWidthOfScreen, kHeightOfScreen)]; _imgVLeft.contentMode = UIViewContentModeScaleAspectFit; [_scrV addSubview:_imgVLeft]; //图片视图;中间 _imgVCenter = [[UIImageView alloc] initWithFrame:CGRectMake(kWidthOfScreen, 0.0, kWidthOfScreen, kHeightOfScreen)]; _imgVCenter.contentMode = UIViewContentModeScaleAspectFit; [_scrV addSubview:_imgVCenter]; //图片视图;右边 _imgVRight = [[UIImageView alloc] initWithFrame:CGRectMake(kWidthOfScreen * 2.0, 0.0, kWidthOfScreen, kHeightOfScreen)]; _imgVRight.contentMode = UIViewContentModeScaleAspectFit; [_scrV addSubview:_imgVRight]; } - (void)addPageControl { _pageC = [UIPageControl new]; CGSize size= [_pageC sizeForNumberOfPages:_imageCount]; //根据页数返回 UIPageControl 合适的大小 _pageC.bounds = CGRectMake(0.0, 0.0, size.width, size.height); _pageC.center = CGPointMake(kWidthOfScreen / 2.0, kHeightOfScreen - 80.0); _pageC.numberOfPages = _imageCount; _pageC.pageIndicatorTintColor = [UIColor whiteColor]; _pageC.currentPageIndicatorTintColor = [UIColor brownColor]; _pageC.userInteractionEnabled = NO; //设置是否允许用户交互;默认值为 YES,当为 YES 时,针对点击控件区域左(当前页索引减一,最小为0)右(当前页索引加一,最大为总数减一),可以编写 UIControlEventValueChanged 的事件处理方法 [self.view addSubview:_pageC]; } - (void)addLabel { _lblImageDesc = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 40.0, kWidthOfScreen, 40.0)]; _lblImageDesc.textAlignment = NSTextAlignmentCenter; _lblImageDesc.textColor = [UIColor whiteColor]; _lblImageDesc.font = [UIFont boldSystemFontOfSize:[UIFont labelFontSize]]; _lblImageDesc.text = @"Fucking now."; [self.view addSubview:_lblImageDesc]; } - (void)setInfoByCurrentImageIndex:(NSUInteger)currentImageIndex { NSString *currentImageNamed = [NSString stringWithFormat:@"%lu.png", (unsigned long)currentImageIndex]; _imgVCenter.image = [UIImage imageNamed:currentImageNamed]; _imgVLeft.image = [UIImage imageNamed:[NSString stringWithFormat:@"%lu.png", (unsigned long)((_currentImageIndex - 1 + _imageCount) % _imageCount)]]; _imgVRight.image = [UIImage imageNamed:[NSString stringWithFormat:@"%lu.png", (unsigned long)((_currentImageIndex + 1) % _imageCount)]]; _pageC.currentPage = currentImageIndex; _lblImageDesc.text = _mDicImageData[currentImageNamed]; } - (void)setDefaultInfo { _currentImageIndex = 0; [self setInfoByCurrentImageIndex:_currentImageIndex]; } - (void)reloadImage { CGPoint contentOffset = [_scrV contentOffset]; if (contentOffset.x > kWidthOfScreen) { //向左滑动 _currentImageIndex = (_currentImageIndex + 1) % _imageCount; } else if (contentOffset.x < kWidthOfScreen) { //向右滑动 _currentImageIndex = (_currentImageIndex - 1 + _imageCount) % _imageCount; } [self setInfoByCurrentImageIndex:_currentImageIndex]; } - (void)layoutUI { self.view.backgroundColor = [UIColor blackColor]; [self loadImageData]; [self addScrollView]; [self addImageViewsToScrollView]; [self addPageControl]; [self addLabel]; [self setDefaultInfo]; } #pragma mark - UIScrollViewDelegate - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { [self reloadImage]; _scrV.contentOffset = CGPointMake(kWidthOfScreen, 0.0); _pageC.currentPage = _currentImageIndex; NSString *currentImageNamed = [NSString stringWithFormat:@"%lu.png", (unsigned long)_currentImageIndex]; _lblImageDesc.text = _mDicImageData[currentImageNamed]; } @end
ImageInfo.plist
来源:KenmuHuang的博客
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