一行iOS代碼實(shí)現(xiàn)圖片無限輪播器

#import <Foundation/Foundation.h>
@interface JFWeakTimerTargetObject : NSObject
+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(nullable id)userInfo repeats:(BOOL)yesOrNo;

@end

#import "JFWeakTimerTargetObject.h"

@interface JFWeakTimerTargetObject ()

@property (nonatomic, weak) id target;
@property (nonatomic, assign) SEL selector;

@end

@implementation JFWeakTimerTargetObject

+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(nullable id)userInfo repeats:(BOOL)yesOrNo {
 //創(chuàng)建當(dāng)前類對(duì)象
 JFWeakTimerTargetObject *object = [[JFWeakTimerTargetObject alloc] init];
 object.target = aTarget;
 object.selector = aSelector;
 return [NSTimer scheduledTimerWithTimeInterval:ti target:object selector:@selector(fire:) userInfo:userInfo repeats:yesOrNo];
}

- (void)fire:(id)obj {
 [self.target performSelector:self.selector withObject:obj];
}

@end

#import <UIKit/UIKit.h>

@interface JFLoopView : UIView

//JFLoopView初始化方法
- (instancetype)initWithImageArray:(NSArray *)imageArray;

@end

#import "JFLoopView.h"

#import "JFLoopViewLayout.h"
#import "JFLoopViewCell.h"
#import "JFWeakTimerTargetObject.h"

@interface JFLoopView () <UICollectionViewDelegate, UICollectionViewDataSource>

@property (nonatomic, strong) UICollectionView *collectionView;
@property (nonatomic, strong) UIPageControl *pageControl;
@property (nonatomic, strong) NSArray *imageArray;
@property (nonatomic, weak) NSTimer *timer;

@end

static NSString *ID = @"loopViewCell";

@implementation JFLoopView

- (instancetype)initWithImageArray:(NSArray *)imageArray {
 if (self = [super init]) {
 UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:[[JFLoopViewLayout alloc] init]];
 [collectionView registerClass:[JFLoopViewCell class] forCellWithReuseIdentifier:ID];
 collectionView.dataSource = self;
 collectionView.delegate = self;
 [self addSubview:collectionView];

 self.collectionView = collectionView;
 self.imageArray = imageArray;

 //添加分頁(yè)器
 [self addSubview:self.pageControl];

 //回到主線程刷新UI
 dispatch_async(dispatch_get_main_queue(), ^{
 //設(shè)置滾動(dòng)的初始狀態(tài)在
 [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:self.imageArray.count inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];

 //添加定時(shí)器
 [self addTimer];
 });

 }
 return self;
}

/// 懶加載pageControl
- (UIPageControl *)pageControl {
 if (!_pageControl) {
 _pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, 220, 0, 30)];
 _pageControl.numberOfPages = self.imageArray.count;
 _pageControl.pageIndicatorTintColor = [UIColor orangeColor];
 _pageControl.currentPageIndicatorTintColor = [UIColor purpleColor];
 }
 return _pageControl;
}

#pragma mark --- UICollectionViewDataSource 數(shù)據(jù)源方法
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
 return self.imageArray.count * 3;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
 JFLoopViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];
 cell.imageName = self.imageArray[indexPath.item % self.imageArray.count];
 return cell;
}

#pragma mark ---- UICollectionViewDelegate

/// 滾動(dòng)完畢就會(huì)調(diào)用（如果不是人為拖拽scrollView導(dǎo)致滾動(dòng)完畢，才會(huì)調(diào)用這個(gè)方法）
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {
 [self scrollViewDidEndDecelerating:scrollView];
}

/// 當(dāng)滾動(dòng)減速時(shí)調(diào)用
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
 CGFloat offsetX = scrollView.contentOffset.x;
 NSInteger page = offsetX / scrollView.bounds.size.width;

 //手動(dòng)滾動(dòng)到左邊臨界狀態(tài)
 if (page == 0) {
 page = self.imageArray.count;
 self.collectionView.contentOffset = CGPointMake(page * scrollView.frame.size.width, 0);
 //滾動(dòng)到右臨界狀態(tài)
 }else if (page == [self.collectionView numberOfItemsInSection:0] - 1) {
 page = self.imageArray.count - 1;
 self.collectionView.contentOffset = CGPointMake(page * scrollView.frame.size.width, 0);
 }

 //設(shè)置UIPageControl當(dāng)前頁(yè)
 NSInteger currentPage = page % self.imageArray.count;
 self.pageControl.currentPage =currentPage;
 //添加定時(shí)器
 [self addTimer];
}

///手指開始拖動(dòng)時(shí)調(diào)用
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
 //移除定時(shí)器
 [self removeTimer];
}

/// 添加定時(shí)器
- (void)addTimer {
 if (self.timer) return;
 self.timer = [JFWeakTimerTargetObject scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
 [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}

/// 移除定時(shí)器
- (void)removeTimer {
 [self.timer invalidate];
 self.timer = nil;
}

/// 切換到下一張圖片
- (void)nextImage {
 CGFloat offsetX = self.collectionView.contentOffset.x;
 NSInteger page = offsetX / self.collectionView.bounds.size.width;
 [self.collectionView setContentOffset:CGPointMake((page + 1) * self.collectionView.bounds.size.width, 0) animated:YES];
}

- (void)layoutSubviews {
 [super layoutSubviews];
 self.collectionView.frame = self.bounds;
}

- (void)dealloc {
 [self removeTimer];
}

@end

#import <UIKit/UIKit.h>
@interface JFLoopViewCell : UICollectionViewCell
@property (nonatomic, copy) NSString *imageName;
@end

#import "JFLoopViewCell.h"
@interface JFLoopViewCell ()
@property (nonatomic, weak) UIImageView *iconView;

@end

@implementation JFLoopViewCell

- (instancetype)initWithFrame:(CGRect)frame {
 if (self = [super initWithFrame:frame]) {
 UIImageView *iconView = [[UIImageView alloc] init];
 [self addSubview:iconView];
 self.iconView = iconView;
 }
 return self;
}

- (void)setImageName:(NSString *)imageName {
 _imageName = imageName;
 self.iconView.image = [UIImage imageNamed:imageName];
}

- (void)layoutSubviews {
 [super layoutSubviews];
 self.iconView.frame = self.bounds;
}

@end

#import <UIKit/UIKit.h>

@interface JFLoopViewLayout : UICollectionViewFlowLayout

@end

#import "JFLoopViewLayout.h"

@implementation JFLoopViewLayout

/// 準(zhǔn)備布局
- (void)prepareLayout {
 [super prepareLayout];

 //設(shè)置item尺寸
 self.itemSize = self.collectionView.frame.size;
 //設(shè)置滾動(dòng)方向
 self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
 //設(shè)置分頁(yè)
 self.collectionView.pagingEnabled = YES;

 //設(shè)置最小間距
 self.minimumLineSpacing = 0;
 self.minimumInteritemSpacing = 0;

 //隱藏水平滾動(dòng)條
 self.collectionView.showsHorizontalScrollIndicator = NO;
}

@end

#import <UIKit/UIKit.h>

@interface JFMainViewController : UIViewController

@end

#import "JFMainViewController.h"

#import "JFLoopView.h"

@interface JFMainViewController ()

@property (nonatomic, strong) JFLoopView *loopView;

@end

@implementation JFMainViewController

- (void)viewDidLoad {
 [super viewDidLoad];

 //關(guān)閉自動(dòng)調(diào)整滾動(dòng)視圖
 self.automaticallyAdjustsScrollViewInsets = NO;
}

- (void)viewWillAppear:(BOOL)animated {
 [super viewWillAppear:animated];
 self.navigationController.navigationBar.hidden = YES;
}

- (void)loadView {
 [super loadView];

 //設(shè)置圖片數(shù)據(jù)
 NSArray *imageArray = @[@"srcoll_01",@"srcoll_02",@"srcoll_03"];

 //此行代碼實(shí)現(xiàn)無限輪播
 _loopView = [[JFLoopView alloc] initWithImageArray:imageArray];

 //設(shè)置loopView的frame
 _loopView.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 250);

 [self.view addSubview:self.loopView];
}

- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}

@end