iOS UIScrollView分页滑动宽度自定义实现
SHAREHONEY
8年前
<h2>前言</h2> <p>App中最常用 <strong>轮播图</strong> , 关于它的实现有很多方法 如 : <strong>Anination, UIScrollView, UICollectionView .</strong> 动画是另一种思路, UICollectionView 继承于 UIScrollView. 作者今天就用 UIScrollView 讲一下 , 分页效果下 滑动宽度小于屏幕宽度 露出上下页内容, 或 滑动视图之间 间隙问题 . 如图 :</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/f3ce57ef9f3d626568c5c156d4310585.png"></p> <p>分页效果下 滑动宽度小于屏幕宽度 露出上下页内容</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/b2b0aca2a8a77a319f633afacce4f3f8.png"></p> <p>滑动视图之间 间隙</p> <h2>一 思路整理</h2> <p>有些文章写过 实现方法, 是把 <strong>pagingEnabled</strong> 设为 <strong>NO</strong> , 自己写出 分页效果. 这么写也可以. 作者更喜欢使用 系统的方法. 实现该效果, 有以下核心代码 :</p> <p>1) <strong>pagingEnabled</strong> 设为 <strong>YES</strong> , 用系统方法实现.</p> <p>2) <strong>clipsToBounds</strong> 设为 <strong>NO</strong> , 为了显现上下页内容</p> <p>3) 分页滑动宽度 系统默认为 <strong>UIScrollView</strong> 的 <strong>width</strong> .</p> <p>4) 算法公式 : <strong> (2 <em>i+ 1)</em> b + i * a </strong> => 说明 : b : 图片间距一半, a : 图片宽</p> <h2>二 封装控件 RollView .h</h2> <pre> <code class="language-objectivec">#import <UIKit/UIKit.h> /** 设置代理 */ @protocol RollViewDelegate <NSObject> -(void)didSelectPicWithIndexPath:(NSInteger)index; @end @interface RollView : UIView @property (nonatomic, assign) id<RollViewDelegate> delegate; /** 初始化 @param frame 设置View大小 @param distance 设置Scroll距离View两侧距离 @param gap 设置Scroll内部 图片间距 @return 初始化返回值 */ - (instancetype)initWithFrame:(CGRect)frame withDistanceForScroll:(float)distance withGap:(float)gap; /** 滚动视图数据 */ -(void)rollView:(NSArray *)dataArr; @end</code></pre> <h2>三 封装控件 RollView .m</h2> <pre> <code class="language-objectivec">#import "RollView.h" @interface RollView ()<UIScrollViewDelegate> @property (nonatomic, strong) UIScrollView *scrollView; @property (nonatomic, strong) NSArray *rollDataArr; // 图片数据 @property (nonatomic, assign) float halfGap; // 图片间距的一半 @end</code></pre> <pre> <code class="language-objectivec">@implementation RollView - (instancetype)initWithFrame:(CGRect)frame withDistanceForScroll:(float)distance withGap:(float)gap { self = [super initWithFrame:frame]; if (self) { self.halfGap = gap / 2; /** 设置 UIScrollView */ self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(distance, 0, self.frame.size.width - 2 * distance, self.frame.size.height)]; [self addSubview:self.scrollView]; self.scrollView.pagingEnabled = YES; self.scrollView.delegate = self; self.scrollView.clipsToBounds = NO; /** 添加手势 */ UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapAction:)]; tap.numberOfTapsRequired = 1; tap.numberOfTouchesRequired = 1; [self.scrollView addGestureRecognizer:tap]; self.scrollView.showsHorizontalScrollIndicator = NO; /** 数据初始化 */ self.rollDataArr = [NSArray array]; } return self; } #pragma mark - 视图数据 -(void)rollView:(NSArray *)dataArr{ self.rollDataArr = dataArr; //循环创建添加轮播图片, 前后各添加一张 for (int i = 0; i < self.rollDataArr.count + 2; i++) { for (UIView *underView in self.scrollView.subviews) { if (underView.tag == 400 + i) { [underView removeFromSuperview]; } } UIImageView *picImageView = [[UIImageView alloc] init]; picImageView.userInteractionEnabled = YES; picImageView.tag = 400 + i ; /** 说明 * 1. 设置完 ScrollView的width, 那么分页的宽也为 width. * 2. 图片宽为a 间距为 gap, 那么 图片应该在ScrollView上居中, 距离ScrollView左右间距为halfGap. * 与 ScrollView的width关系为 width = halfGap + a + halfGap. * 3. distance : Scroll距离 底层视图View两侧距离. * 假设 要露出上下页内容大小为 m , distance = m + halfGap * * 图片位置对应关系 : * 0 -> 2 * halfGap ; * 1 -> 3 * halfGap + a ; * 2 -> 5 * halfGap + 2 * a ; . . * i -> (2 * i +1) * halfGap + 2 *(width - 2 * halfGap ) */ picImageView.frame = CGRectMake((2 * i + 1) * self.halfGap + i * (self.scrollView.frame.size.width - 2 * self.halfGap), 0, (self.scrollView.frame.size.width - 2 * self.halfGap), self.frame.size.height); //设置图片 if (i == 0) { picImageView.image = [UIImage imageNamed:[NSString stringWithFormat:@"%@", self.rollDataArr[self.rollDataArr.count - 1]]]; }else if (i == self.rollDataArr.count+1) { picImageView.image = [UIImage imageNamed:[NSString stringWithFormat:@"%@", self.rollDataArr[0]]]; }else { picImageView.image = [UIImage imageNamed:[NSString stringWithFormat:@"%@", self.rollDataArr[i - 1]]]; } [self.scrollView addSubview:picImageView]; } //设置轮播图当前的显示区域 self.scrollView.contentOffset = CGPointMake(self.scrollView.frame.size.width, 0); self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * (self.rollDataArr.count + 2), 0); } #pragma mark - UIScrollViewDelegate 方法 -(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { NSInteger curIndex = scrollView.contentOffset.x / self.scrollView.frame.size.width; if (curIndex == self.rollDataArr.count + 1) { scrollView.contentOffset = CGPointMake(self.scrollView.frame.size.width, 0); }else if (curIndex == 0){ scrollView.contentOffset = CGPointMake(self.scrollView.frame.size.width * self.rollDataArr.count, 0); } } #pragma mark - 轻拍手势的方法 -(void)tapAction:(UITapGestureRecognizer *)tap{ if ([self.rollDataArr isKindOfClass:[NSArray class]] && (self.rollDataArr.count > 0)) { [_delegate didSelectPicWithIndexPath:(self.scrollView.contentOffset.x / self.scrollView.frame.size.width)]; }else{ [_delegate didSelectPicWithIndexPath:-1]; } }</code></pre> <h2>四 调用</h2> <pre> <code class="language-objectivec">#import "ViewController.h" #import "RollView.h" @interface ViewController ()<RollViewDelegate> @property (nonatomic, strong) RollView *rollView; @end</code></pre> <pre> <code class="language-objectivec">-(void)creatPicRollView{ self.rollView = [[RollView alloc] initWithFrame:CGRectMake(0, 50, self.view.frame.size.width, 150) withDistanceForScroll:12.0f withGap:8.0f]; /**全屏宽滑动 视图之间间隙, 将 Distance 设置为 -12.0f*/ // self.rollView = [[RollView alloc] initWithFrame:CGRectMake(0, 50, self.view.frame.size.width, 150) withDistanceForScroll: -12.0f withGap:8.0f]; // self.rollView.backgroundColor = [UIColor blackColor]; self.rollView.delegate = self; [self.view addSubview:self.rollView]; NSArray *arr = @[@"1.jpg", @"2.jpg", @"3.jpg"]; [self.rollView rollView:arr]; } #pragma mark - 滚动视图协议 -(void)didSelectPicWithIndexPath:(NSInteger)index{ if (index != -1) { NSLog(@"%ld", (long)index); } }</code></pre> <h2>五 效果</h2> <p style="text-align:center"><img src="https://simg.open-open.com/show/1481630fc3583e81bbb02f8ffd207b43.gif"></p> <p>分页效果下 滑动宽度小于屏幕宽度 露出上下页内容</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/0612db9b53d9bf2326344f0811bee44e.gif"></p> <p>滑动视图之间有间隙</p> <p> </p> <p>来自:http://www.jianshu.com/p/9c1be359fd1b</p> <p> </p>