自定義View之無限輪播Banner的實作:STBanner

去年做E4S電商平台APP( PS:平台垮了,沒上線,杯具-_-|| )的時候實作了一個Banner,起初沒想着要實作循環滾動的效果,後來業務提了個問題,要求首頁的banner能夠循環輪播,那時我就奈悶了,蘋果的scrollview好像是沒有循環滾動的吧(PS:那時還是個雛,搞IOS開發沒多久),拔光頭發還想不出,後來通過網絡搜尋,爬貼,各種跪拜...最後得出個點子,就是"n+2".

什麼是”n+2”呢,其實這個方法有點雞肋,别看上去名字好像挺高大上的,說到底就是…就是…第一張左邊添加最後一張,最後一張右邊添加第一張,這就是n+2.很雞肋吧,原理是很簡單,寫成代碼又是另一回事了,當然這裡沒有太過複雜的算法,但是如果封裝得好,感覺也是成就感滿滿的,呵呵!大笑

其實我知道有種方法更好,記得有個設計模式叫享元模式,用這個模式可以讓對象的重用性充分利用,這樣就能夠比較完美了,我想最好的方法應該莫過于此吧…(求大牛莫噴,放過小弟吧,行行好!),但是想到實用性與現實性,必竟banner數量是有限的,是以沒必要寫太複雜,簡單的東西多好!我就喜歡簡單的東西,有同感的親舉手啦!得意

好吧,不說太多廢話了,上代碼吧(這裡可能代碼寫得不怎樣,但為了照顧新手,也為了自已進步,是以放大碼了,讓大家批鬥吧).

首先是STBanner.h檔案,應該不用說都看得懂吧…

#import <UIKit/UIKit.h>

/** 點選回調*/
typedefvoid (^onSelectBlock) (NSInteger selectedIndex);



@interface STBanner :UIView 


/**
 * 初始化STBanner
 *
 * @param bannerArr 圖檔位址數組
 * @param frame 位置大小
 * @return STBanner
 */
+ (instancetype)bannerWithBannerArray:(NSArray *)bannerArr withFrame:(CGRect)frame onSelectBlock:(onSelectBlock)block;


/**
 *銷毀方法
 */
- (void)dead;

@end

然後是STBanner.m檔案,這裡引用了檔案STPageControl.h這個類(這個後面補上),還有SDImage這個類庫:

//*  本循環滾動視圖是  由n+2原理實作的
 //*  簡單來說就是  :   第一張左邊添加最後一張,最後一張右邊添加第一張,這就是n+2


#import "STBanner.h"
#import "STPageControl.h"
#import "UIImageView+WebCache.h"

#define TIMER_DURACTION f
#define kIsOutOfRange


@interface STBanner() <UIScrollViewDelegate>

/** 子滾動視圖*/
@property (nonatomic,strong) UIScrollView *scrollview;
/** 頁面訓示器*/
@property (nonatomic,strong) UIPageControl * pageControl;


/** 圖檔位址數組*/
@property (nonatomic,strong) NSArray *bannerArr;
/** 圖檔容器*/
@property (nonatomic,strong) NSMutableArray * containers;


/** 頁數(是n+2後的頁數,并非實際顯示的頁數)*/
@property (nonatomic,assign) int pageCount;
/** 是否手動拖動*/
@property (nonatomic,assign) BOOL isDragging;


/** 計時器*/
@property (nonatomic,strong) NSTimer *timer;


/** 點選圖檔的回調*/
@property (nonatomic,strong) onSelectBlock block;


@end


@implementation STBanner

#pragma mark - Initialize
- (id)initWithFrame:(CGRect)frame {
   self = [superinitWithFrame:frame];
    NSAssert(self,@"STBanner執行個體化錯誤");
    [selfcommonInit];

    return self;
}

- (void)commonInit {
    [selfaddSubview:self.scrollview];
    [selfaddSubview:self.pageControl];

    UITapGestureRecognizer * tap = [[UITapGestureRecognizeralloc]
                                   initWithTarget:self
                                   action:@selector(bannerTap)];
    [selfaddGestureRecognizer:tap];
    self.userInteractionEnabled =YES;
}

+ (instancetype)bannerWithBannerArray:(NSArray *)bannerArr withFrame:(CGRect)frame onSelectBlock:(onSelectBlock)block
{
   STBanner * banner = [[STBanneralloc]initWithFrame:frame];
    banner.bannerArr = bannerArr?[NSArrayarrayWithArray:bannerArr]:nil ;
    banner.pageCount = (int)bannerArr.count+;
    banner.containers = [NSMutableArrayarray];
    banner.block = block;

    banner.scrollview.contentSize =
   CGSizeMake((frame.size.width * bannerArr.count) + ( * frame.size.width),);
    banner.scrollview.contentOffset =
   CGPointMake(banner.frame.size.width,);
    [banner.scrollviewsetScrollEnabled:bannerArr.count-];

    [banner createContainers];
    bannerArr.count - ? [banner.timersetFireDate:[NSDatedateWithTimeIntervalSinceNow:TIMER_DURACTION]]:NULL;

    banner.pageControl.numberOfPages = banner.bannerArr.count ;

   return banner;
}


- (void)createContainers {
    //初始化圖檔容器
   for (NSInteger i =; i < self.pageCount; i ++) {
       UIImageView * iv    = [[UIImageViewalloc]initWithFrame:
                              CGRectMake(self.frame.size.width * i,
                                         self.frame.origin.y,
                                         self.frame.size.width,
                                         self.frame.size.height)];

        [iv setBackgroundColor:[UIColorcolorWithWhite:falpha:f]];

        [self.scrollviewaddSubview:iv];
        [self.containersaddObject:iv];

        /** 圖檔的加載*/
       NSInteger index;
       if ((i != self.pageCount -) && i)
        {//除第一張和最後一張,都按順序加載圖檔
            index = i-;
        }
       else
        {
           if (i == self.pageCount-)
            {//最後一張用來顯示第一圖檔
                index =;
            }
           else if(!i)
            {//第一張用來顯示最後一張圖檔
                index =self.bannerArr.count-;
            }
        }
        [iv sd_setImageWithURL:[NSURLURLWithString:self.bannerArr[index]]placeholderImage:nil];
    }
}

- (void)layoutSubviews {
    [superlayoutSubviews];
   self.scrollview.frame =self.frame;
    self.pageControl.frame =CGRectMake(self.frame.origin.x,
                                       self.frame.size.height-,
                                       self.frame.size.width,
                                       );
}


#pragma mark - Getters
- (UIScrollView *)scrollview {
    if (!_scrollview) {
       _scrollview = [[UIScrollViewalloc]init];
       _scrollview.delegate =self;
       _scrollview.pagingEnabled =YES ;
        _scrollview.showsHorizontalScrollIndicator =NO ;
        _scrollview.backgroundColor = [UIColorclearColor];

    }
    return_scrollview;
}

- (UIPageControl *)pageControl {
    if (!_pageControl) {
        _pageControl = [[STPageControlalloc]
                        initWithPageIndicatorImageName:@"pagecontrol-thumb-normal"
                        withCurrentPageIndicatorImageName:@"pagecontrol-thumb-selected"];
        _pageControl.pageIndicatorTintColor = [UIColorclearColor];
        _pageControl.currentPageIndicatorTintColor = [UIColorclearColor];
        _pageControl.userInteractionEnabled =NO ;

    }
    return_pageControl;
}

- (NSMutableArray *)containers{
    if (!_containers) {
        _containers = [NSMutableArrayarrayWithCapacity:];
    }
    return_containers;
}

- (NSTimer *)timer{
   if (!_timer) {
        _timer = [NSTimerscheduledTimerWithTimeInterval:TIMER_DURACTIONtarget:selfselector:@selector(changePict)userInfo:nilrepeats:YES];
        [_timersetFireDate:[NSDatedistantFuture]];
    }
   return _timer;
}




#pragma mark - UIScrollViewDelegate
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {

   CGFloat x = scrollView.contentOffset.x ;
    NSInteger index =round(x/[UIScreenmainScreen].bounds.size.width)-;
   self.pageControl.currentPage = index ;

    // 判斷是否手動控制(isTimeUp 的 NO 值 為手動)
    _isDragging?[_timersetFireDate:[NSDatedateWithTimeIntervalSinceNow:TIMER_DURACTION]]:NULL;

    if (x >self.scrollview.contentSize.width -self.frame.size.width)
    {
        [selfscrollToFirst];
    }
   else if(x <=)
    {
        [selfscrollToLast];
    }

}

-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    _isDragging = YES;
}

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    _isDragging = NO;
   CGFloat x = scrollView.contentOffset.x ;
    if (x >self.scrollview.contentSize.width -self.frame.size.width *)
    {

        [selfscrollToFirst];

    }elseif(x == )
    {

        [selfscrollToLast];

    }
}

/** 輪播動畫*/
-(void)changePict {
    CGFloat x = self.scrollview.contentOffset.x +self.frame.size.width;
    [UIViewanimateKeyframesWithDuration:delay:options:UIViewKeyframeAnimationOptionAllowUserInteractionanimations:^ {
        [self.scrollviewsetContentOffset:CGPointMake(x,)];
        if (x >self.scrollview.contentSize.width -self.frame.size.width *)
        {
           self.pageControl.currentPage =;
        }
    }completion:^(BOOL finished) {
        if (x >self.scrollview.contentSize.width -self.frame.size.width *)
        {
            [selfscrollToFirst];

        }
    }];
}

/** 跳到第一張圖檔*/
- (void)scrollToFirst{
    [self.scrollviewsetContentOffset:CGPointMake(self.frame.size.width,)];
}

/** 跳到最後一張圖檔*/
- (void)scrollToLast{
    [self.scrollviewsetContentOffset:CGPointMake(self.frame.size.width*self.bannerArr.count, )];
}




#pragma mark - Actions
-(void)bannerTap {

    self.block&&self.bannerArr.count?
    self.block(self.pageControl.currentPage):NULL;

}


- (void)dead {
    [_pageControlremoveFromSuperview];
    [_timerinvalidate];
    [selfremoveFromSuperview];
}

然後這裡補上STPageControl.h

#import <UIKit/UIKit.h>

@interface STPageControl :UIPageControl

/**
 * 初始化STPageControl
 *
 * @param pageIndicatorImageName
 * @param currentPageIndicatorImageName
 * @return STPageControl
 */
- (instancetype)initWithPageIndicatorImageName:(NSString *)pageIndicatorImageName withCurrentPageIndicatorImageName:(NSString *)currentPageIndicatorImageName;


@end

STPageControl.m

#import "STPageControl.h"

@interface STPageControl (){
   UIImage * _activeImage;
   UIImage *_inactiveImage;
}
@property (nonatomic ,strong)UIImage *activeImage;
@property (nonatomic,strong) UIImage *inactiveImage;
@end

@implementation STPageControl

#pragma mark - Initialize 
- (instancetype)initWithPageIndicatorImageName:(NSString *)pageIndicatorImageName withCurrentPageIndicatorImageName:(NSString *)currentPageIndicatorImageName{

    NSAssert(self = [superinit], @"STPageControl初始化錯誤!");
   _activeImage = [UIImageimageNamed:currentPageIndicatorImageName];
   _inactiveImage = [UIImageimageNamed:pageIndicatorImageName];

    return self;
}


#pragma mark - Setters
- (void)setCurrentPage:(NSInteger)currentPage
{
    [supersetCurrentPage:currentPage];
    [selfupdateDots];
}

/** 替換pageControl小點*/
- (void)updateDots
{
   for (int i =; i< [self.subviewscount]; i++)
    {
       UIView *view = [self.subviewsobjectAtIndex:i];
       CGRect frame = view.frame;
        view.backgroundColor = [UIColorclearColor];
        frame.size.width =f;
        frame.size.height =f;
        view.layer.cornerRadius =f;
        view.frame = frame;

       if (!view.subviews.count) {
            UIImageView *iv = [[UIImageViewalloc]initWithFrame:CGRectMake(,
                                                                          ,
                                                                           frame.size.width,
                                                                           frame.size.height)];
            [viewaddSubview:iv];
        }


       UIImageView  *iv = [view.subviewsfirstObject];
       if (i == self.currentPage)
        {
            [ivsetImage:self.activeImage];
        }
       else
        {
            [ivsetImage:self.inactiveImage];
        }

    }
}

最後寫上ViewController裡的調用例子(很簡單,也許是我寫得好吧!安靜自嘲一下哈)

好,附上ViewController.m檔案内容

#import "ViewController.h"
#import "STBanner.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [superviewDidLoad];
   NSArray *dataArray = @[
                           @"http://pic26.nipic.com/20130121/9475856_141716386357_2.jpg",
                           @"http://pic23.nipic.com/20120823/6854834_144345077352_2.jpg",
                           @"http://pic30.nipic.com/20130626/12977223_211915153000_2.jpg",
                           @"http://pic12.nipic.com/20110124/5375473_153252019000_2.jpg"
                          ];

    [self.viewaddSubview:[STBannerbannerWithBannerArray:dataArray
                                               withFrame:CGRectMake(,
                                                                    ,
                                                                    self.view.frame.size.width,
                                                                    self.view.frame.size.width *f)
                                           onSelectBlock:^(NSInteger selectedIndex)
    {
       NSLog(@"%ld",selectedIndex);
        [selfshowAlertWithMessage:[NSStringstringWithFormat:@"%@",@(selectedIndex)]];
    }]];

    // Do any additional setup after loading the view, typically from a nib.
}

- (void)showAlertWithMessage:(NSString *)message {
    [[[UIAlertViewalloc]initWithTitle:nilmessage:message delegate:nilcancelButtonTitle:@"oklala"otherButtonTitles: nil]show];
}

好了,代碼到此結束,吐cao到此結束!睡覺

自定義View之無限輪播Banner的實作:STBanner

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