iOS实现图片自动切换效果

#import "ViewController.h"
#define ImageViewCount 5
 
@interface ViewController ()<UIScrollViewDelegate>
 
@property (weak, nonatomic) IBOutlet UIScrollView *imageScrollView;
@property (weak, nonatomic) IBOutlet UIPageControl *imageViewPageControl;
@property (strong, nonatomic) NSTimer *timer;
@end
 
@implementation ViewController
 
- (void)viewDidLoad {
 [super viewDidLoad];
 
 [self addImageView2ScrollView];
 self.imageScrollView.contentSize = CGSizeMake(self.imageScrollView.frame.size.width * ImageViewCount, 0);
 
 self.imageScrollView.delegate = self;
 self.imageScrollView.pagingEnabled = YES;//UIScrollView支持拖动分页
 self.imageViewPageControl.numberOfPages = ImageViewCount;
 
 [self addScrollTimer];
}
 
- (void)rotatePic{
 int currentPageIndex = self.imageViewPageControl.currentPage;
 if(++currentPageIndex == 5){
  currentPageIndex = 0;
 }
 CGFloat offsetX = currentPageIndex * self.imageScrollView.frame.size.width;
 [UIView animateWithDuration:1 animations:^{
  self.imageScrollView.contentOffset = CGPointMake(offsetX, 0);
 }];
}
 
/**添加图片到imageScrollView*/
- (void)addImageView2ScrollView{
 CGFloat imageWidth = self.imageScrollView.frame.size.width;
 CGFloat imageHeight = self.imageScrollView.frame.size.height;
 for(int i = 0;i <= ImageViewCount;i++){
  UIImageView *imageInScroll = [[UIImageView alloc] init];
  imageInScroll.frame = CGRectMake(i * imageWidth, 0, imageWidth, imageHeight);
  imageInScroll.image = [UIImage imageNamed:[NSString stringWithFormat:@"img_%02d",i + 1]];
  [self.imageScrollView addSubview:imageInScroll];
 }
}
 
// 正滚动时执行
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
 CGFloat offX = self.imageScrollView.contentOffset.x;//（0，0）距离content内部左上顶点的x轴长度
 NSLog(@"~~~~~~~%f ^^^^^^%f", offX, self.imageScrollView.frame.size.width);
 int currentPageIndex = (offX + .5f * self.imageScrollView.frame.size.width) / self.imageScrollView.frame.size.width;
 self.imageViewPageControl.currentPage = currentPageIndex;
}
 
- (void)addScrollTimer{
 self.timer = [NSTimer timerWithTimeInterval:2 target:self selector:@selector(rotatePic) userInfo:nil repeats:YES];
 [[NSRunLoop mainRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}
 
- (void)removeScrollTimer{
 [self.timer invalidate];//释放定时器
 self.timer = nil;
}
 
// 开始准备滚动时执行 移除定时滚动操作
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
 NSLog(@"~~~scrollViewWillBeginDragging");
 [self removeScrollTimer];
}
 
// 结束滚动后执行 添加定时滚动操作
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
 NSLog(@"~~~scrollViewDidEndDragging");
 [self addScrollTimer];
}
@end