iOS實現無限循環圖片輪播器的封裝
編輯：IOS開發綜合
項目中很多時候會碰到這個需求，實現多張圖片的無限循環輪轉，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，說說我實現循環輪轉圖片的思想，在UIScrollView中添加了3個UIImageView，並排排列，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，這是你滑動到了最後一個UIImageView不能在向左邊滑動了，這時，我在後面悄悄的將第二個UIImageView圖片設置為當前要顯示的圖片，調整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，導致結果你可以向左邊，右邊無線循環輪轉圖片。
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數組，就是你要顯示圖片路徑的數組，將通過這個數組訪問圖片。
JGCirculateSwitchImgView.m文件
typedef NS_ENUM(NSInteger, SwitchDirection)
{
//未成功旋轉
SwitchDirectionNone = -1,
//向右旋轉圖片
SwitchDirectionRight = 0,
//向左訓轉圖片
SwitchDirectionLeft = 1,
};
定義了SwitchDirection枚舉，表示圖片向左，向右輪轉，或者什麼也不做。
//默認5秒訓轉圖片一次,可以根據需要改變 #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; //用於保存當前顯示圖片在圖片urlArr數組中的索引 @property(nonatomic,assign)NSInteger currentImgIndex; //UIScrollView上的三個UIImgaView這裡通過3個UIImageView實現無限循環圖片輪轉 @property(nonatomic,weak)UIImageView *imgView1; @property(nonatomic,weak)UIImageView *imgView2; @property(nonatomic,weak)UIImageView *imgView3; @property(nonatomic,assign)BOOL isDragImgView; //SwitchDirection類型，用於保存滑動的方向 @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,並保證為正值
//這裡很重要，是實現無限循環的重要的一步，比如現在顯示的是第一張圖片，_currentImgIndex=0,向左滑動後就顯示_currentImgIndex+1張圖片，可是_currentImgIndex+1可能回大於_imgUrlArr的數組count，這裡取模，其次還要保證為正數，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，此時加上count保證為正數
-(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)
{
//這裡只使用3個ImgView輪轉多張圖片，數量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), ^{
//循環輪轉圖片
[self switchImg];
});
}
}
5秒旋轉圖片
-(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];
}
旋轉圖片後重新調整3個UIImageView顯示的內容，如實現思想所述
-(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
if (_swDirection == SwitchDirectionLeft)
{
_currentPage = [self switchToValue:_currentPage + 1 Count:_imgUrlArr.count];
}//向右旋轉
else if (_swDirection == SwitchDirectionRight)
{
_currentPage = [self switchToValue:_currentPage - 1 Count:_imgUrlArr.count];
}
_pageControlView.currentPage = _currentPage;
if (_swDirection != SwitchDirectionNone) {
[self switchImgByDirection:_swDirection];
}
_isDragImgView = NO;
}
以上為實現代碼，現在看看怎麼用，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];
可以看到封裝之後，代碼的重用性很高，使用起來很簡單，就這麼4句代碼就可以實現圖片的無限循環輪轉。
以上就是本文的全部內容，希望對大家的學習有所幫助。
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