自定义控件（2） - 性能优化循环图片滚动

功能：

1，显示多张循环滚动的图片；可以加载网络图片（传入url数组）；可以加载本地图片；可以开启和关闭自动循环滚动；三个imageView循环使用不会创建大量

imageView而引起性能问题

注意：

1，需要导入SDWebImage

2，如果使用url显示图片的话，本地图片数组会失效

源码地址：

//
//  BZImageScrollView.h
//  668PetHotel
//
//  Created by 蔡士林 on 15/11/4.
//  Copyright © 2015年 wby. All rights reserved.
//

// BZImageScrollView.h

#import <UIKit/UIKit.h>

@class BZImageScrollView;

@protocol BZImageScrollViewDelegate <NSObject>
/// 点击的图片内容
- (void)imageScrollViewDidClickImage:(BZImageScrollView *)imageScrollView andImageData:(UIImage *)image;
/// 点击的图片下标
- (void)imageScrollViewDidClickImage:(BZImageScrollView *)imageScrollView andClickIndex:(NSInteger)index;
@end

@interface BZImageScrollView : UIView

/// 要滚动显示的图片url数组
@property (strong, nonatomic) NSArray<NSString *> *imageDatas;
/// 要滚动的图片数组（如果有url数组则失效）
@property (strong, nonatomic) NSArray<UIImage *>* photos;

@property (assign, nonatomic) id <BZImageScrollViewDelegate> delegate;
/// 自动滚动
@property (assign, nonatomic, getter=isAutoScroll) BOOL autoScroll;

@end

//
//  BZImageScrollView.m
//  668PetHotel
//
//  Created by 蔡士林 on 15/11/4.
//  Copyright © 2015年 wby. All rights reserved.
//
// BZImageScrollView.m

#import "BZImageScrollView.h"

@interface BZImageScrollView ()<UIScrollViewDelegate>

@property (strong, nonatomic) UIScrollView *mainScrollView;
@property (strong, nonatomic) UIImageView  *leftImageView;
@property (strong, nonatomic) UIImageView  *centerImageView;
@property (strong, nonatomic) UIImageView  *rightImageView;

@property (assign, nonatomic) NSInteger imageCount;
@property (assign, nonatomic) NSInteger currentImageIndex;

@property (strong, nonatomic) UIPageControl *pageControl;
@property (assign, nonatomic) NSInteger pageControlCurrentPage;
@property (strong, nonatomic)  NSTimer *timer;

@end

@implementation BZImageScrollView

- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self setUpUI];
_currentImageIndex = 0;
}
return self;
}

- (void)setUpUI
{
_mainScrollView = [[UIScrollView alloc]init];
_mainScrollView.delegate = self;
_mainScrollView.showsHorizontalScrollIndicator = NO;
_mainScrollView.showsVerticalScrollIndicator   = NO;
_mainScrollView.pagingEnabled = YES;
[self addSubview:_mainScrollView];

_leftImageView = [self imageView];
_centerImageView = [self imageView];
_rightImageView = [self imageView];

self.pageControl = [[UIPageControl alloc]init];
[self addSubview:self.pageControl];
self.pageControl.pageIndicatorTintColor = UIColorFromRGB(KPlaceHolderG);
self.pageControl.currentPageIndicatorTintColor = UIColorFromRGB(kNormalOrange);
}

- (UIImageView *)imageView
{
UIImageView *imageView = [[UIImageView alloc]init];
imageView.userInteractionEnabled = YES;
[_mainScrollView addSubview:imageView];
UITapGestureRecognizer *tapGes = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(imageViewDidClick:)];
[imageView addGestureRecognizer:tapGes];
return imageView;
}

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

_leftImageView.frame = CGRectMake(0, 0, self.width, self.height);
_centerImageView.frame = CGRectMake(self.width, 0, self.width, self.height);
_rightImageView.frame = CGRectMake(self.width * 2, 0, self.width, self.height);
_mainScrollView.contentSize = CGSizeMake(self.width * 3, self.height);
[_mainScrollView setContentOffset:CGPointMake(self.width, 0)];

self.pageControl.centerX = self.self.width/2;
self.pageControl.y = self.height - 20;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
[self mainScrollViewDidScroll:scrollView];
}

- (void)mainScrollViewDidScroll:(UIScrollView *)scrollView
{
if ((self.imageDatas.count != 0 && self.imageDatas != nil) || (self.photos.count != 0)) {
NSInteger allPage = self.imageDatas.count != 0 ? self.imageDatas.count : self.photos.count;
if (scrollView.contentOffset.x > self.width) {
_currentImageIndex = (_currentImageIndex + 1) % self.imageCount;
self.pageControlCurrentPage ++;
if (self.pageControlCurrentPage >= allPage) {
self.pageControlCurrentPage = 0;
}
}
else if (scrollView.contentOffset.x < self.width)
{
_currentImageIndex = (_currentImageIndex + self.imageCount -1) % self.imageCount;
self.pageControlCurrentPage --;
if (self.pageControlCurrentPage < 0) {
self.pageControlCurrentPage = allPage - 1;
}
}
self.pageControl.currentPage = self.pageControlCurrentPage;
if (self.imageDatas.count != 0) {
[_leftImageView sd_setImageWithURL:[NSURL URLWithString:self.imageDatas[(_currentImageIndex + _imageCount - 1) % _imageCount]] placeholderImage:PLACEHOLDER_BIG_IMAGE];
[_rightImageView sd_setImageWithURL:[NSURL URLWithString:self.imageDatas[(_currentImageIndex + 1) % self.imageCount]] placeholderImage:PLACEHOLDER_BIG_IMAGE];
[_centerImageView sd_setImageWithURL:[NSURL URLWithString:self.imageDatas[_currentImageIndex % self.imageCount]] placeholderImage:PLACEHOLDER_BIG_IMAGE];
}
else
{
[_leftImageView setImage:self.photos[(_currentImageIndex + _imageCount - 1) % self.imageCount]];
[_rightImageView setImage:self.photos[(_currentImageIndex + 1) % self.imageCount]];
[_centerImageView setImage:self.photos[_currentImageIndex % self.imageCount]];
}
[scrollView setContentOffset:CGPointMake(self.width, 0)];
}

}

- (void)setImageDatas:(NSArray<NSString *> *)imageDatas
{
_imageDatas = imageDatas;
if (imageDatas.count == 0) {
self.hidden = YES;
}
else
{
self.hidden = NO;
[_centerImageView sd_setImageWithURL:[NSURL URLWithString:imageDatas[0]] placeholderImage:PLACEHOLDER_BIG_IMAGE];
self.imageCount = imageDatas.count;
self.pageControl.numberOfPages = imageDatas.count;
self.pageControl.currentPage = 0;
self.currentImageIndex = 0;
self.pageControlCurrentPage = 0;
}
if (self.isAutoScroll) {
[self beginScroll];
}
}

- (void)setPhotos:(NSArray<UIImage *> *)photos
{
_photos = photos;
if (photos.count == 0) {
self.hidden = YES;
}
else
{
self.hidden = NO;
[_centerImageView setImage:photos[0]];
self.imageCount = photos.count;
self.pageControl.numberOfPages = photos.count;
self.pageControl.currentPage = 0;
self.currentImageIndex = 0;
self.pageControlCurrentPage = 0;
}
if (self.isAutoScroll) {
[self beginScroll];
}
}

- (NSInteger)imageCount
{
if (self.imageDatas.count == 0) {
return self.photos.count;
}
return self.imageDatas.count;
}

- (void)imageViewDidClick:(UITapGestureRecognizer *)tap
{
if ([self.delegate respondsToSelector:@selector(imageScrollViewDidClickImage:andImageData:)]) {
[self.delegate imageScrollViewDidClickImage:self andImageData:((UIImageView *)tap.view).image];
}
if ([self.delegate respondsToSelector:@selector(imageScrollViewDidClickImage:andClickIndex:)]) {
[self.delegate imageScrollViewDidClickImage:self andClickIndex:self.pageControl.currentPage];
}
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
[super touchesBegan:touches withEvent:event];
if (self.timer) {
[self.timer setFireDate:[NSDate distantFuture]];
}
}

- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
[super touchesEnded:touches withEvent:event];
if (self.timer) {
[self.timer setFireDate:[NSDate distantPast]];
}
}

- (void)beginScroll
{
NSTimer *timer = [ NSTimer timerWithTimeInterval:3 target:self selector:@selector(didAutoScroll) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
[timer setFireDate:[NSDate distantPast]];
self.timer = timer;
}

- (void)didAutoScroll
{
[UIView animateWithDuration:0.5 animations:^{
[self.mainScrollView setContentOffset:CGPointMake(self.width * 2, 0)];
} completion:^(BOOL finshed) {
[self mainScrollViewDidScroll:self.mainScrollView];
}];
}

@end