iOS实现图片自动切换效果

2020-02-26 12:01:26 来源:易采站长站 作者:王冬梅

本文实例为大家分享了iOS实现图片自动切换的具体代码,供大家参考,具体内容如下

#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

对UIScrollView的运用,以上代码中有详细注释,需注意2点:

1.注意设置contentSize属性。其中contentSize表示scroll内容尺寸大小

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