IOS中无限滚动Scrollview效果

本文实例讲了IOS无限滚动效果，分享给大家供大家参考，具体内容如下

滑动到当前位置时候才去请求，本地有内容则直接显示（以来SDWebImage,UIView+Ext）
HZScrollView.h

#import <UIKit/UIKit.h>

typedef void(^HZReturnBlock)(NSInteger index,CGFloat offset);

typedef NS_ENUM(NSUInteger, HZScrollViewPageControllPosition) {
 HZScrollViewPageControllPositionNone,
 HZScrollViewPageControllPositionLeft,
 HZScrollViewPageControllPositionCenter,
 HZScrollViewPageControllPositionRight,
};

@class HZScrollView;
@protocol HZScrollViewDelegate <NSObject>

@optional
- (void)resetPosition:(HZScrollView *)scrollView AndIndex:(NSInteger)index;

@end

@interface HZScrollView : UIView
/**
 * 返回当前位置
 */
@property (nonatomic, weak)id <HZScrollViewDelegate>delegate;
/**
 * 默认图
 */
@property (nonatomic, strong) UIImage *hz_placeImage;
/**
 * 图片列表哇
 */
@property (nonatomic, strong) NSArray *hz_ImageList;
/**
 * pagecongroll 位置
 */
@property (nonatomic, assign) HZScrollViewPageControllPosition hz_PageControllPosition;
/**
 * 变换自身frame
 *
 * @param offset 偏移量
 */
- (void)transformView:(CGFloat)offset;
/**
 * 获取当前位置以及便宜
 *
 * @param block 返回内容
 */
- (void)hz_getContent:(HZReturnBlock)block;

@end

HZScrollView.m

#import "UIImageView+WebCache.h"
#import "HZScrollView.h"
#import "UIView+DylanFramTool.h"
#define HZ_FormatImage(val_imageView)\
- (UIImageView *)val_imageView\
{\
if (!_##val_imageView) {\
_##val_imageView = [[UIImageView alloc] init];\
}\
return _##val_imageView;\
}\

//宽度
#define HZ_SWidth self.bounds.size.width
//高度
#define HZ_SHeight self.bounds.size.height

#define HZ_PHeight 16


@interface HZScrollView ()<UIScrollViewDelegate>

@property (nonatomic, copy) HZReturnBlock hz_block;
/**
 * 总数
 */
@property (nonatomic,assign) NSInteger hz_MaxCount;
/**
 * 当前位置
 */
@property (nonatomic,assign) NSInteger hz_currentIndex;
/**
 * 容器
 */
@property (nonatomic, strong) UIScrollView *scrollView;
/**
 * 你懂滴
 */
@property (nonatomic, strong) UIPageControl *pageControll;

/**视图**/
@property (nonatomic, strong) UIImageView *leftImageView;
@property (nonatomic, strong) UIImageView *centerImageView;
@property (nonatomic, strong) UIImageView *rightImageView;

@end

@implementation HZScrollView
{
 CGRect _hz_Frame;
}

#pragma mark -
#pragma mark - init
- (instancetype)initWithFrame:(CGRect)frame
{
 self = [super initWithFrame:frame];
 if (self) {
  _hz_Frame = frame;
  [self addSubview:self.scrollView];
  [self configImageView];
  [self addSubview:self.pageControll];
 }
 return self;
}
#pragma mark -
#pragma mark - config
- (void)configImageView
{
 self.leftImageView.frame = CGRectMake(0, 0, HZ_SWidth, HZ_SHeight);
 [self.scrollView addSubview:self.leftImageView];
 self.centerImageView.frame = CGRectMake(HZ_SWidth, 0, HZ_SWidth, HZ_SHeight);
 [self.scrollView addSubview:self.centerImageView];
 self.rightImageView.frame = CGRectMake(HZ_SWidth * 2, 0, HZ_SWidth, HZ_SHeight);
 [self.scrollView addSubview:self.rightImageView];
}
#pragma mark -
#pragma mark - reSet
- (void)setHz_placeImage:(UIImage *)hz_placeImage
{
 _hz_placeImage = hz_placeImage;
 [self changeImageLeft:-1 center:-1 right:-1];
 if (self.hz_MaxCount) {
  [self setHz_MaxCount:self.hz_ImageList.count];
 }
}
- (void)setHz_ImageList:(NSArray *)hz_ImageList
{
 _hz_ImageList = [hz_ImageList copy];
 [self setHz_MaxCount:_hz_ImageList.count];
}
- (void)setHz_MaxCount:(NSInteger)hz_MaxCount
{
 _hz_MaxCount = hz_MaxCount;

 switch (_hz_MaxCount) {
  case 0:
   self.scrollView.scrollEnabled = NO;
   [self changeImageLeft:-1 center:-1 right:-1];
   break;
  case 1:
   self.scrollView.scrollEnabled = NO;
   [self changeImageLeft:0 center:0 right:0];
   break;

  default:
   self.scrollView.scrollEnabled = YES;
   [self changeImageLeft:_hz_MaxCount - 1 center:0 right:1];
   break;
 }

 self.pageControll.numberOfPages = _hz_MaxCount;
 [self setHz_PageControllPosition:_hz_PageControllPosition];
}
- (void)setHz_PageControllPosition:(HZScrollViewPageControllPosition)hz_PageControllPosition
{
 _hz_PageControllPosition = hz_PageControllPosition;
 CGFloat width = self.hz_MaxCount * HZ_PHeight;
 switch (_hz_PageControllPosition) {
  case HZScrollViewPageControllPositionNone:
   self.pageControll.hidden = YES;
   break;
  case HZScrollViewPageControllPositionLeft:
   self.pageControll.hidden = NO;
   self.pageControll.frame = CGRectMake(10, self.pageControll.frame.origin.y, width, self.pageControll.frame.size.height);
   break;
  case HZScrollViewPageControllPositionCenter:
   self.pageControll.hidden = NO;
   self.pageControll.frame = CGRectMake((self.bounds.size.width - width)/2.f, self.pageControll.frame.origin.y, width, self.pageControll.frame.size.height);
   break;
  case HZScrollViewPageControllPositionRight:
   self.pageControll.hidden = NO;
   self.pageControll.frame = CGRectMake(self.bounds.size.width - 10 - width, self.pageControll.frame.origin.y, width, self.pageControll.frame.size.height);
   break;
  default:
   break;
 }
 if (width <= HZ_PHeight) {
  self.pageControll.hidden = YES;
 }
}
#pragma mark -
#pragma mark - LZ
- (UIScrollView *)scrollView
{
 if (!_scrollView) {
  _scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];
  _scrollView.pagingEnabled = YES;
  _scrollView.showsHorizontalScrollIndicator = NO;
  _scrollView.delegate = self;
  _scrollView.contentSize = CGSizeMake(HZ_SWidth * 3,0);
 }
 return _scrollView;
}
- (UIPageControl *)pageControll
{
 if (!_pageControll) {
  _pageControll = [[UIPageControl alloc] initWithFrame:CGRectMake(0,HZ_SHeight - HZ_PHeight,HZ_PHeight, 7)];
  _pageControll.pageIndicatorTintColor = [UIColor lightGrayColor];
  _pageControll.currentPageIndicatorTintColor = [UIColor whiteColor];
  _pageControll.numberOfPages = self.hz_MaxCount;
  _pageControll.currentPage = 0;
 }
 return _pageControll;
}
HZ_FormatImage(leftImageView);
HZ_FormatImage(centerImageView);
HZ_FormatImage(rightImageView);
#pragma mark -
#pragma mark - private Method

- (void)changeImageWithOffset:(CGFloat)offsetX
{

 if (offsetX >= HZ_SWidth * 2) {
  self.hz_currentIndex++;

  if (self.hz_currentIndex == self.hz_MaxCount - 1) {

   [self changeImageLeft:self.hz_currentIndex - 1 center:self.hz_currentIndex right:0];

  }else if (self.hz_currentIndex == self.hz_MaxCount) {

   self.hz_currentIndex = 0;
   [self changeImageLeft:self.hz_MaxCount - 1 center:0 right:1];

  }else {
   [self changeImageLeft:self.hz_currentIndex-1 center:self.hz_currentIndex right:self.hz_currentIndex + 1];
  }
  if (self.hz_block) {
   self.hz_block(self.hz_currentIndex,offsetX);
  }
  self.pageControll.currentPage = self.hz_currentIndex;

 }

 if (offsetX <= 0) {
  self.hz_currentIndex--;

  if (self.hz_currentIndex == 0) {

   [self changeImageLeft:self.hz_MaxCount-1 center:0 right:1];

  }else if (self.hz_currentIndex == -1) {

   self.hz_currentIndex = self.hz_MaxCount-1;
   [self changeImageLeft:self.hz_currentIndex-1 center:self.hz_currentIndex right:0];

  }else {
   [self changeImageLeft:self.hz_currentIndex-1 center:self.hz_currentIndex right:self.hz_currentIndex+1];
  }
  if (self.hz_block) {
   self.hz_block(self.hz_currentIndex,offsetX);
  }
  self.pageControll.currentPage = self.hz_currentIndex;
 }
 [self setHz_PageControllPosition:_hz_PageControllPosition];

}

- (void)changeImageLeft:(NSInteger)leftIndex center:(NSInteger)centerIndex right:(NSInteger)rightIndex
{
 if (self.hz_currentIndex > self.hz_MaxCount) {
  return;
 }
 if (leftIndex == -1 && centerIndex == -1 && rightIndex == -1) {
  self.leftImageView.image = self.hz_placeImage;
  self.centerImageView.image = self.hz_placeImage;
  self.rightImageView.image = self.hz_placeImage;
 } else {
  [self checkExistImage:self.hz_ImageList[leftIndex]
     ImageView:self.leftImageView
     CurrentIndex:@(leftIndex)];
  [self checkExistImage:self.hz_ImageList[centerIndex]
     ImageView:self.centerImageView
     CurrentIndex:@(centerIndex)] ;
  [self checkExistImage:self.hz_ImageList[rightIndex]
     ImageView:self.rightImageView
     CurrentIndex:@(rightIndex)];
 }
 [self.scrollView setContentOffset:CGPointMake(HZ_SWidth, 0)];

}

- (void)checkExistImage:(NSString *)urlString
    ImageView:(UIImageView *)currentImageView
   CurrentIndex:(NSNumber *)index
{
 if ([[[SDWebImageManager sharedManager] imageCache] imageFromDiskCacheForKey:urlString])
 {
  currentImageView.image = [[[SDWebImageManager sharedManager] imageCache] imageFromMemoryCacheForKey:urlString];
  return;
 } else {
  currentImageView.image = self.hz_placeImage;
  if (self.hz_currentIndex != [index integerValue]) {
   return;
  }
  [self performSelector:@selector(downLoadImage:) withObject:@[urlString,currentImageView] afterDelay:0 inModes:@[NSDefaultRunLoopMode]];
 }

}
- (void)downLoadImage:(NSArray *)param
{
 NSString *urlString = [param firstObject];
 __weak UIImageView *currentImageView = [param lastObject];
 [[SDWebImageManager sharedManager] downloadImageWithURL:[NSURL URLWithString:urlString] options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {
  NSLog(@"received:%@",@(receivedSize));
 } completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
  currentImageView.image = image;
//  [[[SDWebImageManager sharedManager] imageCache] storeImage:image forKey:urlString];
  [[[SDWebImageManager sharedManager] imageCache] storeImage:image forKey:urlString toDisk:YES];
 }];
}
#pragma mark -
#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
 [self changeImageWithOffset:scrollView.contentOffset.x];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
 NSInteger index = scrollView.contentOffset.x/scrollView.width;

 if ([self.delegate respondsToSelector:@selector(resetPosition:AndIndex:)]) {
  [self.delegate resetPosition:self AndIndex:self.hz_currentIndex];
 }
}
#pragma mark -
#pragma mark - public method
- (void)transformView:(CGFloat)offset
{
 if (offset > 0) {
  return;
 }
 CGFloat currentHeight = 210 - offset;
 self.height = currentHeight ;
 CGFloat currentScale = currentHeight / _hz_Frame.size.height;
 self.left = _hz_Frame.origin.x - (_hz_Frame.size.width * currentScale - _hz_Frame.size.width)/2.f;
 self.width = _hz_Frame.size.width * currentScale;
 self.top = offset;

 self.scrollView.size = self.size;

 self.leftImageView.size = self.size;
 self.centerImageView.size = self.size;
 self.rightImageView.size = self.size;

 self.centerImageView.x = self.width;

 self.rightImageView.x = self.width * 2;

 self.scrollView.contentSize = CGSizeMake(self.width *3, self.height);
 [self.scrollView setContentOffset:CGPointMake(HZ_SWidth, 0)];
}

- (void)hz_getContent:(HZReturnBlock)block
{
 self.hz_block = block;
}
- (void)layoutSubviews
{
 [super layoutSubviews];

}

@end

以上就是本文的全部内容，希望对大家的学习有所帮助。