效果圖

UIScrollView - 圖片輪播.gif

#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView; 
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;//分頁指示器
@property (assign, nonatomic) int pageNo; //分頁碼 scrollOffset
@property(nonatomic) int  pageSum;// 總頁數(shù)
@property (assign, nonatomic) CGFloat scrollMaxX; //scrollView最大x軸寬度
@property (assign, nonatomic) CGFloat scrollVisibleW;//scrollView可視區(qū)寬度
@property (assign, nonatomic) CGPoint scrollOffset;//scrollView的偏移量
@property (strong, nonatomic) NSTimer * timerImgScroll;//圖片輪播定時(shí)器
@end


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    UIImage *imageTemp;
    UIImageView *imgViewText;
    
    self.pageSum = 5;// 總頁數(shù)
    CGFloat imgViewY = 0;
    CGFloat imgViewW = 375;
    CGFloat imgViewH = 260;
    
    for (int i=0; i<5; i++) {
        NSString *imgName = [NSString stringWithFormat:@"img_%02d",i+1];
        imageTemp = [UIImage imageNamed:imgName];
        imgViewText = [[UIImageView alloc]initWithImage:imageTemp];
        imgViewText.frame = CGRectMake(i*imgViewW, imgViewY, imgViewW, imgViewH);
        [self.scrollView addSubview:imgViewText];
    }
    //CGFloat imgViewMaxX = CGRectGetMaxX(imgViewText.frame);
    self.scrollMaxX = CGRectGetMaxX(imgViewText.frame);

    //告訴scrollView內(nèi)容有多大
    self.scrollView.contentSize = CGSizeMake(self.scrollMaxX, 0);
    //不顯示水平方向的滾動條
    self.scrollView.showsHorizontalScrollIndicator = NO;
    
    /*
     啟用分頁控件
        scrollView是以多少寬度,進(jìn)行分頁得?
        答:以scrollView自身的寬度為一頁,進(jìn)行分頁得!
     */
    self.scrollView.pagingEnabled = YES;
    
    /*
     PageControl
     Tint Color (其它顏色) Current Color(現(xiàn)在顏色)
     numberOfPages (總共多少頁) currentPage(現(xiàn)在是第幾頁)
     */
    self.pageControl.numberOfPages = self.pageSum;
    
    
    //設(shè)置代理對象
    self.scrollView.delegate = self;
    //設(shè)置scrollView可視區(qū)域的寬度
    CGSize imgViewSize = self.scrollView.frame.size;
    self.scrollVisibleW = imgViewSize.width;

    /*
     第一種方法
     NSTimeInterval 每隔多少時(shí)間
     target:  調(diào)用一次X的
     selector: XX方法
     userInfo: 發(fā)送XX消息
     repeats: 是否重復(fù)
     */
    self.timerImgScroll = [NSTimer scheduledTimerWithTimeInterval: 2.0 target:self selector: @selector(autoImgScoll) userInfo:nil repeats:YES];
    //獲取當(dāng)前運(yùn)行的線程,將’計(jì)時(shí)器’添加到當(dāng)前線程,調(diào)整當(dāng)前線程的優(yōu)先等級
    NSRunLoop *currentLoop = [NSRunLoop currentRunLoop];
    [currentLoop addTimer:self.timerImgScroll forMode:NSRunLoopCommonModes];
}

//自動實(shí)現(xiàn)輪播
-(void)autoImgScoll{
    self.pageNo ++;
    if(self.pageNo >= self.pageSum){
        self.pageNo = 0;
    }
    CGFloat  offsetScroll = (CGFloat)self.pageNo * self.scrollVisibleW;
    self.scrollView.contentOffset = CGPointMake(offsetScroll, 0);
}

/*
 開始拖動,(計(jì)時(shí)器銷毀)
 */
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    NSLog(@"計(jì)時(shí)器銷毀...");
    [self.timerImgScroll invalidate];
}

/*
 結(jié)束拖動
 */
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    NSLog(@"開啟timerBlock計(jì)時(shí)器...");
    /*
     第二種,使用block方式
     當(dāng)前的頁數(shù)*scrollView可視寬度 = 需要移動的偏移量
     timer - block:滿足block里面的條件,方執(zhí)行timer! 不滿足則不執(zhí)行timer
     */
    self.timerImgScroll = [NSTimer scheduledTimerWithTimeInterval:2.0 repeats:YES block:^(NSTimer * _Nonnull timer) {
        self.pageNo++;
        if (self.pageNo >= self.pageSum) {
            self.pageNo = 0;
        }
        CGFloat  offsetScroll = (CGFloat)self.pageNo * self.scrollVisibleW;
        self.scrollView.contentOffset = CGPointMake(offsetScroll, 0);
    }];
    
    //獲取當(dāng)前運(yùn)行的線程,將’計(jì)時(shí)器’添加到當(dāng)前線程,調(diào)整當(dāng)前線程的優(yōu)先等級
    NSRunLoop *currentLoop = [NSRunLoop currentRunLoop];
    [currentLoop addTimer:self.timerImgScroll forMode:NSRunLoopCommonModes];
}

/*
 監(jiān)聽滾動事件
 通過偏移量,來計(jì)算出滾動到某個(gè)寬度,則PageControl跳轉(zhuǎn)到下一個(gè)
    計(jì)算公式: (滾動的偏移量 + 每頁寬度*0.5)/每頁的寬度 = 第幾頁
    計(jì)算公式: 滾動的偏移量/每頁的寬度 + 0.5 = 第幾頁
 */
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    
    NSLog(@"%@",NSStringFromCGPoint(self.scrollView.contentOffset));
    //獲取滾動時(shí)的偏移量
    self.scrollOffset = self.scrollView.contentOffset;
    
    //self.pageNo = scrollOffset.x/self.scrollVisibleW;
    
    //最初方法沒有*0.5,這樣如果將圖片滾動到中間位置,pageControl不會改變?yōu)橄乱豁?就是那個(gè)點(diǎn),不會改變)!
    //self.pageNo = self.scrollOffset.x /self.scrollVisibleW;
    self.pageNo = (self.scrollOffset.x + self.scrollVisibleW *0.5)/self.scrollVisibleW;
    self.pageControl.currentPage = self.pageNo;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}
@end