iOS开发学习--纯代码 UIScrollView 无限循环的实现——代码类封装

一个简单的利用UIScrollView 实现的无线滚动banner,下面的代码实现，因为封装问题，对两个及一下的view 支持出了一点问题（view是传参进来的，不可以生成两份），但是原理是正确的，智者见智吧

先说一下原理，看下面的图

第一种原理       ， 本文是用的原理

为了方便看懂，这里做了2张动图

下面是解析图

    

第二种原理

原理清晰了，代码附上，有问题可以留言，会尽快回复，

.h文件

//
//  MyUIScrollView.h
//  UIscrollView
//
//  Created by Ibokan on 15/8/25.
//  Copyright (c) 2015年 Crazy凡. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface MyUIScrollView : NSObject
@property (nonatomic,strong)UIScrollView *scrollView; //滚动框
@property (nonatomic,strong)UILabel * label;//titlelabel，要想显示图片title 需要先将label 贴到view中，并且settitle，如果不调用settitle 方法，则不会显示
@property (nonatomic,strong)UIPageControl * pageControl;//显示小点
//以上三个控件都需要调用 [self.view addSubView:]方法，否则不会显示
@property BOOL isCarousel;//是否有动画  默认有 View  数量为一张  会关闭动画
@property double delay;//动画播放速度 默认1.5 最小应 > 0.2
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num Margin:(int)margin;//frame是全部尺寸,num是View数量,margin是内容和外边框距离
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num MarginV:(int)marginV MarginH:(int)marginH;//垂直和水平边距
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num MarginT:(int)marginTop MarginR:(int)marginRight MarginB:(int)marginBottom MarginL:(int)marginLeft;//上右下左边距
- (void)setSubView:(NSArray *)viewArray;//填充view,最好多于2个，数量为2的请复制成4个，数量为1的将不允许滑动，2个以上的不需要做特殊处理
- (void)setTitle:(NSArray *)title;
@end

.m 文件

//
//  MyUIScrollView.m
//  UIscrollView
//
//  Created by Ibokan on 15/8/25.
//  Copyright (c) 2015年 Crazy凡. All rights reserved.
//

#import "MyUIScrollView.h"

@interface MyUIScrollView () <UIScrollViewDelegate>
@property (nonatomic,strong)NSTimer * timer;
@property (nonatomic,strong)NSMutableArray *labeltitle;
@property (nonatomic,strong)NSMutableArray *viewArray;
@property (nonatomic,strong)NSMutableArray *titleArray;
@property int indexc;
@property BOOL isOne; //记录图片是否只有一张
@end

@implementation MyUIScrollView
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num Margin:(int)margin
{
    [self makeWF:frame VN:num MT:margin MR:margin MB:margin ML:margin];
    return self;
}
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num MarginV:(int)marginV MarginH:(int)marginH
{
    [self makeWF:frame VN:num MT:marginV MR:marginH MB:marginV ML:marginH];
    return self;
}
- (instancetype)initWithFrame:(CGRect)frame ViewNum:(int)num MarginT:(int)marginTop MarginR:(int)marginRight MarginB:(int)marginBottom MarginL:(int)marginLeft;
{
    [self makeWF:frame VN:num MT:marginTop MR:marginRight MB:marginBottom ML:marginLeft];
    return self;
}
- (void) makeWF:(CGRect)frame VN:(int)num MT:(int)marginT MR:(int)marginR MB:(int)marginB ML:(int)marginL
{
    _isOne = num == 1 ? YES : NO ;
    self.label = [[UILabel alloc] initWithFrame: CGRectMake(0,frame.size.height-60,frame.size.width,20)];
    self.label.textAlignment = NSTextAlignmentCenter;//label 初始化
    self.pageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(frame.size.width - num * 17 ,frame.size.height-30,num * 15, 20)];
    self.pageControl.numberOfPages = num;
    self.indexc = 0; 
    num = 3;
    self.scrollView = [[UIScrollView alloc]initWithFrame:frame];
    self.scrollView.pagingEnabled = YES;
    self.scrollView.delegate = self;
    self.scrollView.contentSize = CGSizeMake(frame.size.width * num , frame.size.height);
    int i = 0;
    while(i < num){
        UIView *v = [[UIView alloc]initWithFrame:CGRectMake(i * frame.size.width + marginL, marginT, frame.size.width - marginL - marginR, frame.size.height - marginT - marginB)];
        v.clipsToBounds = YES;
        [self.scrollView addSubview:v];
        i++;
    }
    CGPoint point =  CGPointMake(frame.size.width,0);
    self.scrollView.contentOffset = point;
    self.scrollView.showsHorizontalScrollIndicator = NO;
    self.isCarousel = YES;//默认自动交换
    self.isCarousel ? self.timer = [NSTimer scheduledTimerWithTimeInterval:3 target:self selector:@selector(autochange) userInfo:nil repeats:YES] : nil;
}
- (int)checkindex:(int)temp
{
    return (temp < 0 ? temp = (int)(self.viewArray.count -1) : (temp == (int)(self.viewArray.count) ? 0 : temp));
}
- (void)autochange//自动切换
{
    _isOne ? nil : [UIView animateWithDuration:(self.delay > 0.2 ? self.delay : 1.5 )  animations:^{ self.scrollView.contentOffset = CGPointMake( self.scrollView.frame.size.width * 2 - 1 , 0); } completion:^(BOOL finished) { self.scrollView.contentOffset = CGPointMake( self.scrollView.frame.size.width * 2 , 0); }];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    self.scrollView.contentOffset = _isOne ? CGPointMake(self.scrollView.frame.size.width,0) : self.scrollView.contentOffset ;// 只有一张图，强行不允许移动
    if((int)self.scrollView.contentOffset.x == 0)
    {
        self.indexc = [self checkindex:--self.indexc];
        [self changeimg];
    }
    if(fabs(self.scrollView.contentOffset.x - 2 * self.scrollView.frame.size.width) < 1e-10)
    {
        self.indexc = [self checkindex:++self.indexc];
        [self changeimg];
    }
}
- (void)changeimg
{
    self.scrollView.contentOffset = CGPointMake(self.scrollView.frame.size.width,0);
    [self.scrollView.subviews[0] addSubview:_viewArray[[self checkindex:(self.indexc-1)]]];
    [self.scrollView.subviews[2] addSubview:_viewArray[[self checkindex:(self.indexc+1)]]]; 
    [self.scrollView.subviews[1] addSubview:_viewArray[self.indexc]];
    self.pageControl.currentPage = self.indexc;
    _labeltitle ? [self.label setText:_labeltitle[self.indexc]]:nil;
}
- (void)setSubView:(NSArray *)viewArray
{
    _viewArray = [[NSMutableArray alloc]initWithArray:viewArray];
    [self changeimg];
}
- (void)setTitle:(NSArray *)title
{
    _labeltitle = [[NSMutableArray alloc]initWithArray:title];
    [self.label setText:_labeltitle[0]];
}
@end

代码被封装了，可以直接用我写的这个类生成一个变量，代码中有对各个属性的解释

代码源文件