iOS实现带有缩放效果的自动轮播图

#import <UIKit/UIKit.h>  @interface CustomScrollView : UIView @property (strong,nonatomic) NSArray *imageArr;  @end 

#import "CustomScrollView.h"  @interface CustomScrollView ()<UIScrollViewDelegate>  @property (strong,nonatomic) UIScrollView *scrollView; @property (strong,nonatomic) UIImageView *backImageView;  @property (strong,nonatomic) UIImageView *leftIamgeView; @property (strong,nonatomic) UIImageView *middleImageView; @property (strong,nonatomic) UIImageView *rightImageView;  @property (strong,nonatomic) UIPageControl *pageControl;  //高度 @property (assign,nonatomic) CGFloat scrollViewHeight;  //手动造成的偏移量 @property (assign,nonatomic) CGFloat offsetX;  @property (strong,nonatomic) NSTimer *timer;  //属于计时器方法动画持续时间 ？ @property (assign,nonatomic) BOOL timerAnimation;  @end  //左右内容的最大偏移量 #define OFFSET_MAX ([UIScreen mainScreen].bounds.size.width-64)*0.9   @implementation CustomScrollView  - (instancetype)initWithFrame:(CGRect)frame {  if (self = [super initWithFrame:frame]) {   self.scrollViewHeight = frame.size.height;   [self addSubview:self.backImageView];  [self addSubview:self.scrollView];  [self addSubview:self.pageControl];   [self.backImageView mas_makeConstraints:^(MASConstraintMaker *make) {  make.edges.with.mas_equalTo(self);  }];  [self.scrollView mas_makeConstraints:^(MASConstraintMaker *make) {  make.edges.with.mas_equalTo(self);  }];  [self.pageControl mas_makeConstraints:^(MASConstraintMaker *make) {  make.left.right.bottom.mas_equalTo(self);  make.height.mas_equalTo(@20);  }];   self.timer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(timerAction) userInfo:nil repeats:YES];  [[NSRunLoop mainRunLoop] addTimer:self.timer forMode:NSDefaultRunLoopMode];  [self.timer setFireDate:[NSDate dateWithTimeIntervalSinceNow:5]];  }  return self; }  - (NSArray *)imageArr {  if (!_imageArr) {  _imageArr = @[@"timg-0",@"timg-1",@"timg-2"];  }  return _imageArr; }  - (UIImageView *)backImageView {  if (!_backImageView) {  _backImageView = [[UIImageView alloc] init];  _backImageView.image = [UIImage imageNamed:@"bg_home"];  }  return _backImageView; }  - (UIScrollView *)scrollView {  if (!_scrollView) {  _scrollView = [[UIScrollView alloc] init];  _scrollView.showsVerticalScrollIndicator = NO;  _scrollView.showsHorizontalScrollIndicator = NO;  _scrollView.contentSize = CGSizeMake(kScreenWidth+2*OFFSET_MAX, self.scrollViewHeight);  [_scrollView setContentOffset:CGPointMake(OFFSET_MAX, 0)];  _scrollView.bounces = NO;  _scrollView.delegate = self;   _leftIamgeView = [[UIImageView alloc] init];  _leftIamgeView.image = [UIImage imageNamed:self.imageArr[0]];  _leftIamgeView.layer.cornerRadius = 5;  _leftIamgeView.layer.masksToBounds = YES;    _middleImageView = [[UIImageView alloc] init];  _middleImageView.image = [UIImage imageNamed:self.imageArr[1]];  _middleImageView.layer.cornerRadius = 5;  _middleImageView.layer.masksToBounds = YES;    _rightImageView = [[UIImageView alloc] init];  _rightImageView.image = [UIImage imageNamed:self.imageArr[2]];  _rightImageView.layer.cornerRadius = 5;  _rightImageView.layer.masksToBounds = YES;    [_scrollView addSubview:_leftIamgeView];  [_scrollView addSubview:_middleImageView];  [_scrollView addSubview:_rightImageView];  [_leftIamgeView mas_makeConstraints:^(MASConstraintMaker *make) {  make.size.mas_equalTo(CGSizeMake((kScreenWidth-64)*0.9, self.scrollViewHeight*0.9));  make.centerY.mas_equalTo(_scrollView);  make.right.mas_equalTo(_middleImageView.mas_left).offset(-20);  }];  [_middleImageView mas_makeConstraints:^(MASConstraintMaker *make) {  make.size.mas_equalTo(CGSizeMake(kScreenWidth-64, self.scrollViewHeight));  make.centerY.mas_equalTo(_scrollView);  make.left.mas_equalTo(_scrollView).offset(OFFSET_MAX+64/2);  }];  [_rightImageView mas_makeConstraints:^(MASConstraintMaker *make) {  make.size.mas_equalTo(_leftIamgeView);  make.centerY.mas_equalTo(_scrollView);  make.left.mas_equalTo(_middleImageView.mas_right).offset(20);  }];  }  return _scrollView; }  - (UIPageControl *)pageControl {  if (!_pageControl) {  _pageControl = [[UIPageControl alloc] init];  _pageControl.numberOfPages = self.imageArr.count;  _pageControl.enabled = NO;  _pageControl.currentPage = 0;  _pageControl.hidesForSinglePage = YES;  _pageControl.pageIndicatorTintColor = [UIColor whiteColor];  _pageControl.currentPageIndicatorTintColor = MAINCOLOR;  }  return _pageControl; }   #pragma mark ------------ UIScrollViewDelegate --------  - (void)scrollViewDidScroll:(UIScrollView *)scrollView {  if (self.timerAnimation) {  return;  }  CGFloat offScale = scrollView.contentOffset.x - OFFSET_MAX;  if (offScale < 0) {  //右滑  self.leftIamgeView.layer.transformScale = 1 + 1.0/9*(fabs(offScale)/OFFSET_MAX);  self.middleImageView.layer.transformScale = 1 - 0.1*(fabs(offScale)/OFFSET_MAX);  } else {  //左滑  self.rightImageView.layer.transformScale = 1 + 1.0/9*(fabs(offScale)/OFFSET_MAX);  self.middleImageView.layer.transformScale = 1 - 0.1*(fabs(offScale)/OFFSET_MAX);  }  }  - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {  CGPoint offset = scrollView.contentOffset;   self.offsetX = offset.x;   if ((fabs(self.offsetX-OFFSET_MAX) >= OFFSET_MAX*0.5)) {  if (!decelerate) {  //替换图片  [self exchangeImage];  }  } else {  //回弹复位  [scrollView setContentOffset:CGPointMake(OFFSET_MAX, 0) animated:YES];  self.leftIamgeView.layer.transform = CATransform3DIdentity;  self.middleImageView.layer.transform = CATransform3DIdentity;  self.rightImageView.layer.transform = CATransform3DIdentity;  } }  - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {  //替换图片  [self exchangeImage]; }  #pragma mark ---------- exchangeImage ------ //替换图片 - (void)exchangeImage {  if (self.offsetX-OFFSET_MAX < 0) {  //右滑  UIImage *rightImage = self.rightImageView.image;  self.rightImageView.image = self.middleImageView.image;  self.middleImageView.image = self.leftIamgeView.image;  self.leftIamgeView.image = rightImage;   if (self.pageControl.currentPage - 1 < 0) {  self.pageControl.currentPage = self.pageControl.numberOfPages-1;  } else {  self.pageControl.currentPage -= 1;  }   } else {  //左滑  UIImage *leftImage = self.leftIamgeView.image;  self.leftIamgeView.image = self.middleImageView.image;  self.middleImageView.image = self.rightImageView.image;  self.rightImageView.image = leftImage;   if (self.pageControl.currentPage + 1 >= self.pageControl.numberOfPages) {  self.pageControl.currentPage = 0;  } else {  self.pageControl.currentPage += 1;  }  }  [self.scrollView setContentOffset:CGPointMake(OFFSET_MAX, 0)];  self.leftIamgeView.layer.transform = CATransform3DIdentity;  self.middleImageView.layer.transform = CATransform3DIdentity;  self.rightImageView.layer.transform = CATransform3DIdentity; }  #pragma mark ---------- timer -------- - (void)timerAction {  self.offsetX = kScreenWidth+OFFSET_MAX-64;   self.timerAnimation = YES;  [UIView animateWithDuration:0.8 animations:^{  [self.scrollView setContentOffset:CGPointMake(self.offsetX, 0)];  self.rightImageView.layer.transformScale = 10/9.0;  self.middleImageView.layer.transformScale = 0.9;  } completion:^(BOOL finished) {  self.timerAnimation = NO;  [self exchangeImage];  self.rightImageView.layer.transform = CATransform3DIdentity;  self.middleImageView.layer.transform = CATransform3DIdentity;  }]; }  @end 

self.scrollView = [[CustomScrollView alloc] initWithFrame:CGRectMake(0, 0, kScreenWidth, 170)]; [self.view addSubview:self.scrollView];