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iOS实现无限循环图片轮播器的封装

转载 作者:qq735679552 更新时间:2022-09-28 22:32:09 26 4
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 项目中很多时候会碰到这个需求,实现多张图片的无限循环轮转,以前做过,项目中几个地方的都用到了,当时没有封装,几个地方都拷贝几乎一样的代码,代码复用性不好,今天没事封装了一下,使用起来比较简单.

  首先,说说我实现循环轮转图片的思想,在UIScrollView中添加了3个UIImageView,并排排列,我们看到的永远只是第二个UIImageView,这样的话,你一直可以向左,向右滑动,当你向左滑动是,这是你滑动到了最后一个UIImageView不能在向左边滑动了,这时,我在后面悄悄的将第二个UIImageView图片设置为当前要显示的图片,调整UIScrollView的contentOffset属性,如:

[_contentScrollView setContentOffset:CGPointMake(self.bounds.size.width, 0) animated:NO](使用者根本感觉不出来这种变化)所以,此时,你看到的又是第二个UIImageView,所以此时你又可以向左滑动,当你向右边滑动时候处理类似,导致结果你可以向左边,右边无线循环轮转图片.

JGCirculateSwitchImgView.h头文件 。

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@interface JGCirculateSwitchImgView : UIView
@property(nonatomic,strong)NSArray *imgUrlArr;
@end

  头文件中只有一个需要设置的成员变量imgUrlArr数组,就是你要显示图片路径的数组,将通过这个数组访问图片.

JGCirculateSwitchImgView.m文件 。

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typedef NS_ENUM(NSInteger, SwitchDirection)
 
{
 
//未成功旋转
  SwitchDirectionNone = -1,
//向右旋转图片
  SwitchDirectionRight = 0,
//向左训转图片
SwitchDirectionLeft = 1,
 
};

定义了SwitchDirection枚举,表示图片向左,向右轮转,或者什么也不做.

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//默认5秒训转图片一次,可以根据需要改变
#define WiatForSwitchImgMaxTime 5
#import "JGCirculateSwitchImgView.h"
#import "UIImageView+WebCache.h"
@interface JGCirculateSwitchImgView ()
 
//底部UIScrollView
@property(nonatomic,weak)UIScrollView *contentScrollView;
//显示页码的UIPageControl控件
@property(nonatomic,weak)UIPageControl *pageControlView;
//用保存当前UIPageControl控件显示的当前位置
@property(nonatomic,assign)NSInteger currentPage;
//用于保存当前显示图片在图片urlArr数组中的索引
@property(nonatomic,assign)NSInteger currentImgIndex;
//UIScrollView上的三个UIImgaView这里通过3个UIImageView实现无限循环图片轮转
@property(nonatomic,weak)UIImageView *imgView1;
@property(nonatomic,weak)UIImageView *imgView2;
@property(nonatomic,weak)UIImageView *imgView3;
@property(nonatomic,assign) BOOL isDragImgView;
//SwitchDirection类型,用于保存滑动的方向
@property(nonatomic,assign)SwitchDirection swDirection;
 
@end
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-(id)initWithFrame:(CGRect)frame
 
{
 
   if (self = [super initWithFrame:frame])
   {
     [self createContentScrollView];
     [self createPageControlView];
    //默认第一页
    _currentPage = 0;
    //默认显示第一张图片
    _currentImgIndex = 0;
    _isDragImgView = NO;
    _swDirection = SwitchDirectionNone;
 
   }
 
    return self;
 
}

创建UIScrollView代码 。

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-( void )createContentScrollView
 
{
 
   UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];
   scrollView.delegate = self;
   scrollView.showsHorizontalScrollIndicator = NO;
   scrollView.shouldGroupAccessibilityChildren = NO;
   scrollView.pagingEnabled = YES;
   [self addSubview:scrollView];
   _contentScrollView = scrollView;
 
}

创建UIPageControl 。

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-( void )createPageControlView
 
{
 
   UIPageControl *pageControlVw = [[UIPageControl alloc] init];
   pageControlVw.frame = CGRectMake(0, 0, 80, 20);
   pageControlVw.center = CGPointMake(self.center.x, self.bounds.size.height - 20);
   pageControlVw.backgroundColor = [UIColor redColor];
   _pageControlView.pageIndicatorTintColor = [UIColor yellowColor];
   _pageControlView.currentPageIndicatorTintColor = [UIColor purpleColor];
   [self addSubview:pageControlVw];
   _pageControlView = pageControlVw;
 
}
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//value对Count取模,并保证为正值
 
//这里很重要,是实现无限循环的重要的一步,比如现在显示的是第一张图片,_currentImgIndex=0,向左滑动后就显示_currentImgIndex+1张图片,可是_currentImgIndex+1可能回大于_imgUrlArr的数组count,这里取模,其次还要保证为正数,比如,如果向右边滑动是就显示_currentImgIndex-1张图片,_currentImgIndex-1取模也可能为负数,此时加上count保证为正数
 
-(NSInteger)switchToMValue:(NSInteger)value Count:(NSInteger)count
 
{
 
   NSInteger result = value % count;
   return result >=0 ? result : result + count;
 
}

重写imgUrlArr的set方法 。

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-( void )setImgUrlArr:(NSArray *)imgUrlArr
 
{
 
   _imgUrlArr = [imgUrlArr copy];
   NSInteger count = imgUrlArr.count;
   if (count <= 0 )
   {
    return ;
   }
 
   //如果只显示一张图片,那就没有旋转情况
   if (count == 1)
 
   {
 
     UIImageView *imgView = [[UIImageView alloc]init];
     imgView.frame = CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height);
    [_contentScrollView addSubview:imgView];
    _pageControlView.numberOfPages = 1;
    _pageControlView.currentPage = 0;
    _contentScrollView.contentSize = CGSizeMake(self.bounds.size.width, self.bounds.size.height);
    NSURL *imgUrl = [NSURL URLWithString:imgUrlArr[0]];
    [imgView sd_setImageWithURL:imgUrl placeholderImage:nil];
    return ;
 
   }
 
   if (count > 1)
 
   {
 
      //这里只使用3个ImgView轮转多张图片,数量2,3,4,5,6...
      for ( int i = 0; i < 3 ;i++)
      {
 
        UIImageView *imgView = [[UIImageView alloc] init];
        imgView.frame = CGRectMake(i * self.bounds.size.width, 0, self.bounds.size.width, self.bounds.size.height);
        imgView.layer.masksToBounds = YES;
        NSString *urlStr = urlStr = _imgUrlArr[[self switchToValue:i-1 Count:count]];
        NSURL *imgUrl = [NSURL URLWithString:urlStr];
        [imgView sd_setImageWithURL:imgUrl placeholderImage:nil];
        if (i == 0)
 
        {
 
          _imgView1 = imgView;
 
         }
 
         else if (i == 1)
 
        {
 
          _imgView2 = imgView;
 
        }
 
        else if (i == 2)
 
        {
 
          _imgView3 = imgView;
 
        }
 
        [_contentScrollView addSubview:imgView];
 
      }
 
     _pageControlView.numberOfPages = count;
     _pageControlView.currentPage = 0;
     _contentScrollView.contentSize = CGSizeMake(self.bounds.size.width * 3,  self.bounds.size.height);
     _currentImgIndex = 0;
     [_contentScrollView setContentOffset:CGPointMake(self.bounds.size.width, 0) animated:NO];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
       //循环轮转图片
       [self switchImg];
 
    });
 
   }
 
}

5秒旋转图片 。

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-( void )switchImg
 
{
 
    while (1)
 
    {
 
      [NSThread sleepForTimeInterval:WiatForSwitchImgMaxTime];
      //如果正在拖拽图片,此次作废
       if (_isDragImgView) {
         continue ;
 
       }
 
       _currentPage = [self switchToValue:_currentPage + 1 Count:_imgUrlArr.count];
       dispatch_async(dispatch_get_main_queue(), ^{
          _pageControlView.currentPage = _currentPage;
          _contentScrollView.contentOffset = CGPointMake(2 * self.bounds.size.width, 0);
          [self reSetImgUrlWithDirection:SwitchDirectionLeft];
 
      });
 
    }
 
}

当手动旋转图片 。

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-( void )switchImgByDirection:(SwitchDirection)direction
 
{
 
    if (direction == SwitchDirectionNone) {
      return ;
    }
    [self reSetImgUrlWithDirection:direction];
    [_contentScrollView setContentOffset:CGPointMake(self.bounds.size.width, 0) animated:NO];
 
}

旋转图片后重新调整3个UIImageView显示的内容,如实现思想所述 。

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-( void )reSetImgUrlWithDirection:(SwitchDirection)direction
 
{
 
    if (direction == SwitchDirectionRight) {
      [_imgView1 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex - 2 Count:_imgUrlArr.count]]] placeholderImage:nil];
      [_imgView2 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex - 1 Count:_imgUrlArr.count]]] placeholderImage:nil];
      [_imgView3 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex Count:_imgUrlArr.count]]] placeholderImage:nil];
      _currentImgIndex = [self switchToValue:_currentImgIndex - 1 Count:_imgUrlArr.count];
 
    }
    else if (direction == SwitchDirectionLeft)
 
    {
      [_imgView1 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex Count:_imgUrlArr.count]]] placeholderImage:nil];
      [_imgView2 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex + 1 Count:_imgUrlArr.count]]] placeholderImage:nil];
      [_imgView3 sd_setImageWithURL:[NSURL URLWithString:_imgUrlArr[[self switchToValue:_currentImgIndex + 2 Count:_imgUrlArr.count]]] placeholderImage:nil];
      _currentImgIndex = [self switchToValue:_currentImgIndex + 1 Count:_imgUrlArr.count];
 
    }
 
}

实现UIScrollVie3个代理方法 。

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#pragma mark -------------Delegate---------------
 
//记住滑动的方向
 
- ( void )scrollViewDidScroll:(UIScrollView *)scrollView
 
{
 
   static float newx = 0;
   static float oldx = 0;
   newx= scrollView.contentOffset.x ;
   if (newx != oldx )
   {
     if (newx > oldx)
     {
       _swDirection = SwitchDirectionLeft;
 
     } else if (newx < oldx)
 
    {
      _swDirection = SwitchDirectionRight;
 
    }
 
    oldx = newx;
 
   }
 
}
 
- ( void )scrollViewWillBeginDragging:(UIScrollView *)scrollView
 
{
 
   _isDragImgView = YES;
 
}
 
- ( void )scrollViewDidEndDecelerating:(UIScrollView *)scrollView
 
{
 
    //向左旋转
    if (_swDirection == SwitchDirectionLeft)
    {
      _currentPage = [self switchToValue:_currentPage + 1 Count:_imgUrlArr.count];
 
    } //向右旋转
    else if (_swDirection == SwitchDirectionRight)
 
    {
      _currentPage = [self switchToValue:_currentPage - 1 Count:_imgUrlArr.count];
 
    }
    _pageControlView.currentPage = _currentPage;
    if (_swDirection != SwitchDirectionNone) {
    [self switchImgByDirection:_swDirection];
 
    }
 
   _isDragImgView = NO;
 
}

以上为实现代码,现在看看怎么用,例如:

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JGCirculateSwitchImgView *jView = [[JGCirculateSwitchImgView alloc] initWithFrame:CGRectMake(20,100, 280, 250)];
 
NSArray *imgUrlArr = @[@ "http://www.blisscake.cn/Upload/Product/Show/Source/ps_1507201119031647109.jpg" ,
 
@ "http://www.blisscake.cn/Upload/Product/Show/Source/ps_1507201116215754685.jpg" ,
@ "http://www.blisscake.cn/Upload/Product/Show/Source/ps_1507201115524758041.jpg" ,
@ "http://www.blisscake.cn/Upload/Product/Show/Source/ps_1507201114495822068.jpg" ,
@ "http://www.blisscake.cn/Upload/Product/Show/Source/ps_1507201107522493367.jpg" ];
jView.imgUrlArr = imgUrlArr;
[self.view addSubview:jView];

可以看到封装之后,代码的重用性很高,使用起来很简单,就这么4句代码就可以实现图片的无限循环轮转.

以上就是本文的全部内容,希望对大家的学习有所帮助.

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