iOS實現(xiàn)無限循環(huán)圖片輪播器的封裝

更新時間：2016年03月22日 14:44:34 作者：jiangamh

這篇文章主要為大家詳細介紹了iOS實現(xiàn)無限循環(huán)圖片輪播器的封裝，文中示例代碼介紹的非常詳細，具有一定的參考價值，感興趣的小伙伴們可以參考一下

項目中很多時候會碰到這個需求，實現(xiàn)多張圖片的無限循環(huán)輪轉(zhuǎn)，以前做過，項目中幾個地方的都用到了，當時沒有封裝，幾個地方都拷貝幾乎一樣的代碼，代碼復用性不好，今天沒事封裝了一下，使用起來比較簡單。

首先，說說我實現(xiàn)循環(huán)輪轉(zhuǎn)圖片的思想，在UIScrollView中添加了3個UIImageView，并排排列，我們看到的永遠只是第二個UIImageView，這樣的話，你一直可以向左，向右滑動，當你向左滑動是，這是你滑動到了最后一個UIImageView不能在向左邊滑動了，這時，我在后面悄悄的將第二個UIImageView圖片設置為當前要顯示的圖片，調(diào)整UIScrollView的contentOffset屬性，如：

[_contentScrollView setContentOffset:CGPointMake(self.bounds.size.width, 0) animated:NO]（使用者根本感覺不出來這種變化）所以，此時，你看到的又是第二個UIImageView，所以此時你又可以向左滑動，當你向右邊滑動時候處理類似，導致結(jié)果你可以向左邊，右邊無線循環(huán)輪轉(zhuǎn)圖片。

JGCirculateSwitchImgView.h頭文件

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

頭文件中只有一個需要設置的成員變量imgUrlArr數(shù)組，就是你要顯示圖片路徑的數(shù)組，將通過這個數(shù)組訪問圖片。

JGCirculateSwitchImgView.m文件

typedef NS_ENUM(NSInteger, SwitchDirection)

{

//未成功旋轉(zhuǎn)
 SwitchDirectionNone = -1,
//向右旋轉(zhuǎn)圖片
 SwitchDirectionRight = 0,
//向左訓轉(zhuǎn)圖片
SwitchDirectionLeft = 1,

};

定義了SwitchDirection枚舉，表示圖片向左，向右輪轉(zhuǎn)，或者什么也不做。

//默認5秒訓轉(zhuǎn)圖片一次,可以根據(jù)需要改變
#define WiatForSwitchImgMaxTime 5
#import "JGCirculateSwitchImgView.h"
#import "UIImageView+WebCache.h"
@interface JGCirculateSwitchImgView ()

//底部UIScrollView
@property(nonatomic,weak)UIScrollView *contentScrollView;
//顯示頁碼的UIPageControl控件
@property(nonatomic,weak)UIPageControl *pageControlView;
//用保存當前UIPageControl控件顯示的當前位置
@property(nonatomic,assign)NSInteger currentPage;
//用于保存當前顯示圖片在圖片urlArr數(shù)組中的索引
@property(nonatomic,assign)NSInteger currentImgIndex;
//UIScrollView上的三個UIImgaView這里通過3個UIImageView實現(xiàn)無限循環(huán)圖片輪轉(zhuǎn)
@property(nonatomic,weak)UIImageView *imgView1;
@property(nonatomic,weak)UIImageView *imgView2;
@property(nonatomic,weak)UIImageView *imgView3;
@property(nonatomic,assign)BOOL isDragImgView;
//SwitchDirection類型，用于保存滑動的方向
@property(nonatomic,assign)SwitchDirection swDirection;

@end

-(id)initWithFrame:(CGRect)frame

{

  if (self = [super initWithFrame:frame])
  {
    [self createContentScrollView];
    [self createPageControlView];
   //默認第一頁
   _currentPage = 0;
   //默認顯示第一張圖片
   _currentImgIndex = 0;
   _isDragImgView = NO;
   _swDirection = SwitchDirectionNone;

  }

   return self;

}

創(chuàng)建UIScrollView代碼

-(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;

}

創(chuàng)建UIPageControl

-(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;

}

//value對Count取模,并保證為正值

//這里很重要，是實現(xiàn)無限循環(huán)的重要的一步，比如現(xiàn)在顯示的是第一張圖片，_currentImgIndex=0,向左滑動后就顯示_currentImgIndex+1張圖片，可是_currentImgIndex+1可能回大于_imgUrlArr的數(shù)組count，這里取模，其次還要保證為正數(shù)，比如，如果向右邊滑動是就顯示_currentImgIndex-1張圖片，_currentImgIndex-1取模也可能為負數(shù)，此時加上count保證為正數(shù)

-(NSInteger)switchToMValue:(NSInteger)value Count:(NSInteger)count

{

  NSInteger result = value % count;
  return result >=0 ? result : result + count;

}

重寫imgUrlArr的set方法

-(void)setImgUrlArr:(NSArray *)imgUrlArr

{

  _imgUrlArr = [imgUrlArr copy];
  NSInteger count = imgUrlArr.count;
  if (count <= 0 )
  {
   return;
  }

  //如果只顯示一張圖片,那就沒有旋轉(zhuǎn)情況
  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)

  {

     //這里只使用3個ImgView輪轉(zhuǎn)多張圖片，數(shù)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), ^{
      //循環(huán)輪轉(zhuǎn)圖片
      [self switchImg];

   });

  }

}

5秒旋轉(zhuǎn)圖片

-(void)switchImg

{

   while (1)

   {

     [NSThread sleepForTimeInterval:WiatForSwitchImgMaxTime];
     //如果正在拖拽圖片，此次作廢 
      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];

     });

   }

}

當手動旋轉(zhuǎn)圖片

-(void)switchImgByDirection:(SwitchDirection)direction

{

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

}

旋轉(zhuǎn)圖片后重新調(diào)整3個UIImageView顯示的內(nèi)容，如實現(xiàn)思想所述

-(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];

   }

}

實現(xiàn)UIScrollVie3個代理方法

#pragma mark -------------Delegate---------------

//記住滑動的方向

- (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

{

   //向左旋轉(zhuǎn)
   if (_swDirection == SwitchDirectionLeft)
   {
     _currentPage = [self switchToValue:_currentPage + 1 Count:_imgUrlArr.count];

   }//向右旋轉(zhuǎn)
   else if (_swDirection == SwitchDirectionRight)

   {
     _currentPage = [self switchToValue:_currentPage - 1 Count:_imgUrlArr.count];

   }
   _pageControlView.currentPage = _currentPage;
   if (_swDirection != SwitchDirectionNone) {
   [self switchImgByDirection:_swDirection];

   }

  _isDragImgView = NO;

}

以上為實現(xiàn)代碼，現(xiàn)在看看怎么用，例如：

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];

可以看到封裝之后，代碼的重用性很高，使用起來很簡單，就這么4句代碼就可以實現(xiàn)圖片的無限循環(huán)輪轉(zhuǎn)。

以上就是本文的全部內(nèi)容，希望對大家的學習有所幫助。

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