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];