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  • 自定义轮播图、自定义集合控件的实现

    首先声明本篇博客是个人原创，绝非抄袭。

    自定义实现轮播图

    轮播图一般实现在一款App的首页的最上部分，能够来回滚动的图片，通常这些图片都对应一个网络Url ,用户点击的时候，能够跳转到对应的UIwebView页面。轮播图也可以使用在用户引导页面，只不过这时候轮播图的大小是全屏的，用户可以在轮播图上放一些控件，用来收集用户的信息，当用户进入程序的时候，可以根据这些信息，加载相应的版块内容，或者推荐相应的推送。轮播图也可以在相框的程序中用到，也可以在新闻类App中对应一个专题的整页的滑动，总之轮播图增添了App的用户体验效果，是必不可少的一个技术实现。

    本文的轮播图采用工具：

    UIScrollView（用于实现轮播效果）、UILabel（用于显示当前是第几张）、NSTimer（用于实现自动轮播）采用封装的思想，降低耦合度，将该功能组件化。

    目前实现的功能相对来说比较简单，功能如下：

    能够设置轮播图的位置大小、设置录播的一组图片用数组实现、是否自动轮播、自动轮播间隔时间。

    使用：

    首先引入ScrollerImage.h 和 ScrollerImage.m文件到工程中

    调用接口：

    -(id)initWithFrame:(CGRect)frame

                  Arrary:(NSArray *)imageArr

            isAutomLunBo:(BOOL)isYes

            setLunBoTime:(NSInteger)intervalTime;

    例如：

    在一个视图控制器中

    #import "ScrollerImage.h"//引入自定义轮播图

    @property(nonatomic,strong)ScrollerImage * myImageViewScroller;

     //轮播图的图片数组

                    NSArray * arrImg = @[@"1.png",@"2.png",@"3.png",@"4.png",@"5.png",@"6.png",@"7.png",@"8.png",@"9.png"];

                    self.myImageViewScroller = [[ScrollerImage alloc]initWithFrame:view.frame Arrary:arrImg isAutomLunBo:NO setLunBoTime:2.3];

                    [view addSubview:self.myImageViewScroller];

     代码：

    #import <UIKit/UIKit.h>

@interface ScrollerImage : UIView<UIScrollViewDelegate>
@property(assign)NSInteger count;

-(id)initWithFrame:(CGRect)frame
              Arrary:(NSArray *)imageArr
        isAutomLunBo:(BOOL)isYes
        setLunBoTime:(NSInteger)intervalTime;

-(void)dealloc;
@end
    View Code  ScrollerImage.h
    #import "ScrollerImage.h"

@interface ScrollerImage ()

@property (strong, nonatomic)  UIScrollView *scroll;
@property (strong, nonatomic)  UILabel *toKonwCurrentPageLabel;
@property(strong,nonatomic)NSTimer * timer;

@property(assign)int n;

@end

@implementation ScrollerImage

//自定义轮播图
-(id)initWithFrame:(CGRect)frame Arrary:(NSArray *)imageArr isAutomLunBo:(BOOL)isYes setLunBoTime:(NSInteger)intervalTime;{
    
    if ([super init]) {
        self.frame = frame;
    }
    self.count = imageArr.count;
    CGFloat kWidth = self.frame.size.width;
    CGFloat kHeight = self.frame.size.height;
    //滑块
    self.scroll = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, kWidth, kHeight)];
    self.scroll.contentSize = CGSizeMake(kWidth * imageArr.count, kHeight);
    self.scroll.pagingEnabled = YES;
    self.scroll.delegate = self;
    self.scroll.scrollEnabled = YES;
    [self addSubview:self.scroll];
    //显示图片张数
    self.toKonwCurrentPageLabel = [[UILabel alloc]initWithFrame:CGRectMake(kWidth - 90, kHeight - 30, 60, 20)];
    self.toKonwCurrentPageLabel.layer.masksToBounds = YES;
    self.toKonwCurrentPageLabel.layer.cornerRadius = 11;
    self.toKonwCurrentPageLabel.backgroundColor = [UIColor blackColor];
    self.toKonwCurrentPageLabel.textColor = [UIColor whiteColor];
    self.toKonwCurrentPageLabel.textAlignment = NSTextAlignmentCenter;
    self.toKonwCurrentPageLabel.font = [UIFont systemFontOfSize:12];
    self.toKonwCurrentPageLabel.alpha = 0.3;
    self.toKonwCurrentPageLabel.text = [NSString stringWithFormat:@"1/共%lu张",self.count];
    for (int i = 0; i < imageArr.count; i++) {
        UIImageView * viewImage = [[UIImageView alloc]initWithFrame:CGRectMake(i*kWidth, 0, kWidth, kHeight)];
        viewImage.image = [UIImage imageNamed:imageArr[i]];
        [self.scroll addSubview:viewImage];
    }
    [self.scroll addSubview:self.toKonwCurrentPageLabel];
    [self.scroll bringSubviewToFront:self.toKonwCurrentPageLabel];
    //轮播效果
    if (isYes == YES) {
        self.timer = [NSTimer timerWithTimeInterval:intervalTime target:self selector:@selector(LunBoAction:) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop]addTimer:self.timer forMode:NSRunLoopCommonModes];
    }
    self.n = 0;//初始化轮播位置
    return self;
}

//LunBo
-(void)LunBoAction:(NSTimer *)sender{
    self.n +=1;
    self.scroll.contentOffset = CGPointMake(self.scroll.frame.size.width * (self.n % (int)self.count), 0);
    int i = self.n %(int)self.count;
    [self setLabelWith:i contentOffset:self.scroll.frame.size.width andHeight:self.scroll.frame.size.height];
    if (self.n == self.count) {
        self.n = 0;
    }
}
//人为滑动图片
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    CGFloat width = scrollView.frame.size.width;
    CGFloat height = scrollView.frame.size.height;
   self.n  =  scrollView.contentOffset.x/width;
    [self setLabelWith:self.n contentOffset:width andHeight:height];
}
-(void)setLabelWith:(int)i contentOffset:(CGFloat)width andHeight:(CGFloat)height{
    self.toKonwCurrentPageLabel.text = [NSString stringWithFormat:@"%d/共%lu张",i+1,self.count];
    self.toKonwCurrentPageLabel.frame = CGRectMake(width*(i + 1) - 90, height - 30 , 60, 20);
}

-(void)dealloc{
    self.timer = nil;
    [self.timer invalidate];
    
}
@end
    View Code  ScrollerImage.m

    效果截图：

     

    自定义集合控件的实现

    集合视图也能够实现轮播图，我觉得有时间再次研究轮播图的实现，下面使用到集合视图是解决这类问题，看下面的两幅图片，左边的是在请求数据后解析的结果没有录播图，并且上面四个主题“附近的贴”“精编推荐”。。是不固定的主题，有可能某一天主题变化为两个，下面6个主题的板块主题个数也是有可能变化的,主题的多少是根据请求到的数组里的主题个数决定，这里仅仅是模拟功能。右边的图片中，有轮播图，上下两个板块的功能与图片一中的是一样的。

    技术点分析：

    首先因为主题有可能要变化，根据界面的设计需求，所以最好是使用集合视图UICollectionView 实现。而是否有轮播图可以使用一个布尔值判断，如果有轮播图就开启集合视图的页眉，如果没有就关闭集合视图的页眉，并动态的改变位置。比较难以实现的是，如何在一个 UIViewController 中实现有两个 UICollectionView

    ，对于这个问题，可以在 UICollectionViewDelegate 的协议方法中，根据可重用ID做一下判断即可。 

    有录播图，两个板块主题内容不固定                  

    实现功能的全部源代码：

    需要源代码的园友可以在左侧QQ我哦，如有转载请说明出处，谢谢。

    #import <UIKit/UIKit.h>

@interface ViewController : UIViewController


@end
    View Code ViewController.m 
    #import "ViewController.h"
#import "Cell.h"
#import "HeaderView.h"
#import "FooterView.h"
#import "ScrollerImage.h"//引入自定义轮播图

@interface ViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>
{
    BOOL isHaveLunBo;//判断是否有轮播图
}
@property(nonatomic,strong)UIScrollView * scroll;
@property(nonatomic,strong)ScrollerImage * myImageViewScroller;

@property(nonatomic,strong)UICollectionView * collectionView1;
@property(nonatomic,strong)UICollectionView * collectionView2;

//测试数据
@property(nonatomic,strong)NSMutableArray * arrayOfTestDataSouce1;
@property(nonatomic,strong)NSMutableArray * arrayOfTestDataSouce2;


@end

@implementation ViewController

//-lazy
-(NSMutableArray *)arrayOfTestDataSouce1{
    if (_arrayOfTestDataSouce1 == nil) {
        //我在这里给数据添加数据，可以在请求到数据后再添加数据
        NSArray * testArr = @[@"A",@"B",@"C",@"D"];
        self.arrayOfTestDataSouce1 = [NSMutableArray arrayWithArray:testArr];
        NSLog(@"%@",self.arrayOfTestDataSouce1);
    }
    return _arrayOfTestDataSouce1;
}


-(NSMutableArray *)arrayOfTestDataSouce2{
    if (_arrayOfTestDataSouce2 == nil) {
        //我在这里给数据添加数据，可以在请求到数据后再添加数据
        NSArray * testArr = @[@"AA",@"BB",@"CC",@"DD",@"EE",@"FF"];
        self.arrayOfTestDataSouce2 = [NSMutableArray arrayWithArray:testArr];
        NSLog(@"%@",self.arrayOfTestDataSouce2);
    }
    return _arrayOfTestDataSouce2;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //关闭毛玻璃效果
    self.navigationController.navigationBar.translucent = NO;
    
    //添加 集合视图1
    UIView * vi = [[UIView alloc] init];
    vi.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 125);
    vi.backgroundColor = [UIColor redColor];
    
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    //配置属性
    //1.设置每个item的大小
    layout.itemSize = CGSizeMake(self.view.bounds.size.width / 2 - 10, 50);
    //2.设置缩进量 （上，左，下，右）
    layout.sectionInset = UIEdgeInsetsMake(0, 5, 0, 5);
    //3.设置行的最小间距
    layout.minimumLineSpacing = 2.5;
    //4.设置item的最小间距
    layout.minimumInteritemSpacing = 10;
    
   
    self.collectionView1 = [[UICollectionView alloc] initWithFrame:vi.frame collectionViewLayout:layout];
    //这里巨坑啊，设定代理一定要写到初始化集合视图的下面
    self.collectionView1.delegate = self;
    self.collectionView1.dataSource = self;
    self.collectionView1.backgroundColor = [UIColor brownColor];

    [vi addSubview:self.collectionView1];
    [self.view addSubview:vi];
    
    //判断是否有轮播图(默认有-YES)
    isHaveLunBo = YES;
    
    
    //添加 集合视图2
    UICollectionViewFlowLayout *layout2 = [[UICollectionViewFlowLayout alloc] init];
    //配置属性
    //1.设置每个item的大小
    layout2.itemSize = CGSizeMake(50, 50);
    //2.设置缩进量 （上，左，下，右）
    layout2.sectionInset = UIEdgeInsetsMake(0, 5, 0, 5);
    //3.设置行的最小间距
    layout2.minimumLineSpacing = 10;
    //4.设置item的最小间距
    layout2.minimumInteritemSpacing = 10;
    
    
    //设置大小
    if (isHaveLunBo) {
            self.collectionView2 = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 125, self.collectionView1.frame.size.width, 180 + 125) collectionViewLayout:layout2];
    }else{
           self.collectionView2 = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 125, self.collectionView1.frame.size.width, 180) collectionViewLayout:layout2];
    }

    self.collectionView2.delegate = self;
    self.collectionView2.dataSource = self;
    [self.view addSubview:self.collectionView2];
    
    
    //注册cell
    [self.collectionView1 registerClass:[Cell class] forCellWithReuseIdentifier:@"item1"];
    [self.collectionView2 registerClass:[Cell class] forCellWithReuseIdentifier:@"item2"];
    
    //注册页眉
    [self.collectionView1 registerClass:[HeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];
    [self.collectionView2 registerClass:[FooterView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footer"];
    //注册页脚
    [self.collectionView2 registerClass:[HeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];
    [self.collectionView2 registerClass:[FooterView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footer"];
    
}



#pragma mark - UICollectionViewDataSource -
//设置分区的item数目
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    if (collectionView == self.collectionView1) {
        return self.arrayOfTestDataSouce1.count;
    }
    else {
        return self.arrayOfTestDataSouce2.count;
    }
 
}

//设置分区数目
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    if (collectionView == self.collectionView1) {
        return 1;
    }
    else {
        return 1;
    }

}

#pragma Mark======设置自定义的cell
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
  
    if (collectionView == self.collectionView1) {
              Cell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"item1" forIndexPath:indexPath];
    cell.lab.text = self.arrayOfTestDataSouce1[indexPath.item];
    cell.lab.frame = cell.bounds;
    
    return cell;
    }
    else {
        Cell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"item2" forIndexPath:indexPath];
        cell.lab.text = self.arrayOfTestDataSouce2[indexPath.item];
        return cell;
    }
}

#pragma Mark======设置页眉与页脚的视图
-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{
    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
       
        if (collectionView == self.collectionView2) {
            //返回页眉
            HeaderView * view = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"header" forIndexPath:indexPath];
            //view.titleLabel.text = @"页眉，可以在黄色区域放轮播图";
            
            if (isHaveLunBo == YES) {
                //轮播图的图片数组
                NSArray * arrImg = @[@"1.png",@"2.png",@"3.png",@"4.png",@"5.png",@"6.png",@"7.png",@"8.png",@"9.png"];
                self.myImageViewScroller = [[ScrollerImage alloc]initWithFrame:view.frame Arrary:arrImg isAutomLunBo:NO setLunBoTime:2.3];
                [view addSubview:self.myImageViewScroller];
                return view;
            }else{
                return nil;
            }
        }else{
            return nil;
        }
        
    } else {
        //返回页脚
//        FooterView *footer = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"footer" forIndexPath:indexPath];
//        footer.footerLabel.text = @"页脚";
//        return footer;
        return nil;
    }

}


#pragma mark - UICollectionViewDelegateFlowLayout -
//动态配置每个分区的item的size大小
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    if (indexPath.section == 0) {
        return CGSizeMake((self.view.frame.size.width - 15)/2, 50);
    }
    return CGSizeMake((self.view.frame.size.width - 60)/3, 50);
}
//动态配置item的缩进量
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
    if (section == 0) {
        //上、左、下、右
        return UIEdgeInsetsMake(10, 5, 10, 5);
    }
    return UIEdgeInsetsMake(10, 5, 10, 5);
}
//动态配置item 左右最小间距
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
    return 5;
}
//动态配置行的最小间距
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 5;
}
//动态的设置页眉
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{
    
    if (collectionView == self.collectionView1) {
        //这里也可以仿照下面写法，为 collectionView1 设定是否添加页眉
        return CGSizeMake(0, 0);
    }else{
        if (isHaveLunBo) {
            return CGSizeMake(20, 100);
        }else{
            return CGSizeMake(0, 0);
        }
       
    }
    
}

//动态的设置页脚
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section{
    return CGSizeMake(0, 0);
}

#pragma mark - UICollectionViewDelegate -
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
//选中某一行的点击事件写这里
    NSLog(@"选择了");
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end
    View Code ViewController.m 
    #import <UIKit/UIKit.h>

@interface ScrollerImage : UIView<UIScrollViewDelegate>
@property(assign)NSInteger count;

-(id)initWithFrame:(CGRect)frame
              Arrary:(NSArray *)imageArr
        isAutomLunBo:(BOOL)isYes
        setLunBoTime:(NSInteger)intervalTime;

-(void)dealloc;
@end
    View Code ScrollerImage.h
    #import "ScrollerImage.h"

@interface ScrollerImage ()

@property (strong, nonatomic)  UIScrollView *scroll;
@property (strong, nonatomic)  UILabel *toKonwCurrentPageLabel;
@property(strong,nonatomic)NSTimer * timer;

@property(assign)int n;

@end

@implementation ScrollerImage

//自定义轮播图
-(id)initWithFrame:(CGRect)frame Arrary:(NSArray *)imageArr isAutomLunBo:(BOOL)isYes setLunBoTime:(NSInteger)intervalTime;{
    
    if ([super init]) {
        self.frame = frame;
    }
    self.count = imageArr.count;
    CGFloat kWidth = self.frame.size.width;
    CGFloat kHeight = self.frame.size.height;
    //滑块
    self.scroll = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, kWidth, kHeight)];
    self.scroll.contentSize = CGSizeMake(kWidth * imageArr.count, kHeight);
    self.scroll.pagingEnabled = YES;
    self.scroll.delegate = self;
    self.scroll.scrollEnabled = YES;
    [self addSubview:self.scroll];
    //显示图片张数
    self.toKonwCurrentPageLabel = [[UILabel alloc]initWithFrame:CGRectMake(kWidth - 90, kHeight - 30, 60, 20)];
    self.toKonwCurrentPageLabel.layer.masksToBounds = YES;
    self.toKonwCurrentPageLabel.layer.cornerRadius = 11;
    self.toKonwCurrentPageLabel.backgroundColor = [UIColor blackColor];
    self.toKonwCurrentPageLabel.textColor = [UIColor whiteColor];
    self.toKonwCurrentPageLabel.textAlignment = NSTextAlignmentCenter;
    self.toKonwCurrentPageLabel.font = [UIFont systemFontOfSize:12];
    self.toKonwCurrentPageLabel.alpha = 0.3;
    self.toKonwCurrentPageLabel.text = [NSString stringWithFormat:@"1/共%lu张",self.count];
    for (int i = 0; i < imageArr.count; i++) {
        UIImageView * viewImage = [[UIImageView alloc]initWithFrame:CGRectMake(i*kWidth, 0, kWidth, kHeight)];
        viewImage.image = [UIImage imageNamed:imageArr[i]];
        [self.scroll addSubview:viewImage];
    }
    [self.scroll addSubview:self.toKonwCurrentPageLabel];
    [self.scroll bringSubviewToFront:self.toKonwCurrentPageLabel];
    //轮播效果
    if (isYes == YES) {
        self.timer = [NSTimer timerWithTimeInterval:intervalTime target:self selector:@selector(LunBoAction:) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop]addTimer:self.timer forMode:NSRunLoopCommonModes];
    }
    self.n = 0;//初始化轮播位置
    return self;
}

//LunBo
-(void)LunBoAction:(NSTimer *)sender{
    self.n +=1;
    self.scroll.contentOffset = CGPointMake(self.scroll.frame.size.width * (self.n % (int)self.count), 0);
    int i = self.n %(int)self.count;
    [self setLabelWith:i contentOffset:self.scroll.frame.size.width andHeight:self.scroll.frame.size.height];
    if (self.n == self.count) {
        self.n = 0;
    }
}
//人为滑动图片
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    CGFloat width = scrollView.frame.size.width;
    CGFloat height = scrollView.frame.size.height;
   self.n  =  scrollView.contentOffset.x/width;
    [self setLabelWith:self.n contentOffset:width andHeight:height];
}
-(void)setLabelWith:(int)i contentOffset:(CGFloat)width andHeight:(CGFloat)height{
    self.toKonwCurrentPageLabel.text = [NSString stringWithFormat:@"%d/共%lu张",i+1,self.count];
    self.toKonwCurrentPageLabel.frame = CGRectMake(width*(i + 1) - 90, height - 30 , 60, 20);
}

-(void)dealloc{
    self.timer = nil;
    [self.timer invalidate];
    
}
@end
    View Code ScrollerImage.m
    #import <UIKit/UIKit.h>

@interface FooterView : UICollectionReusableView
@property (nonatomic, retain) UILabel *footerLabel;

@end
    View Code FooterView.h
    #import "FooterView.h"

@implementation FooterView
- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self addSubview:self.footerLabel];
    }
    return self;
}

- (UILabel *)footerLabel {
    if (!_footerLabel) {
        self.footerLabel = [[UILabel alloc] initWithFrame:self.bounds];
        _footerLabel.backgroundColor = [UIColor greenColor];
    }
    return _footerLabel;
}

@end
    View Code FooterView.m
    #import <UIKit/UIKit.h>


@interface HeaderView : UICollectionReusableView
@property (nonatomic, retain) UILabel *titleLabel;

@end
    View Code HeaderView.h
    #import "HeaderView.h"

@implementation HeaderView


- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self addSubview:self.titleLabel];
    }
    return self;
}

- (UILabel *)titleLabel {
    if (!_titleLabel) {
        self.titleLabel = [[UILabel alloc] initWithFrame:self.bounds];
        _titleLabel.backgroundColor = [UIColor yellowColor];
    }
    return _titleLabel;
}

@end
    View Code HeaderView.m
    #import <UIKit/UIKit.h>

@interface Cell : UICollectionViewCell

@property(nonatomic,strong)UILabel * lab;

@end
    View Code Cell.h
    #import "Cell.h"

@implementation Cell

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        //按照此格式，添加一些其他控件
        [self.contentView addSubview:self.lab];
    }
    return self;
}


- (UILabel *)lab {
    if (!_lab) {
        self.lab = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
        //测试颜色
        _lab.backgroundColor = [UIColor greenColor];
        
        _lab.textAlignment = NSTextAlignmentCenter;
        _lab.font = [UIFont systemFontOfSize:15];
    }
    return _lab;
}

@end
    View Code Cell.m

    源代码实现效果：

    左边图片假设没有请求到轮播图，右边图片假设请求到轮播图，关键代码

    isHaveLunBo = YES;如果为NO，不显示录播图，具体情况根据网络请求结果处理，这里仅仅模拟效果。

                      

    单单就轮播图实现了优化：
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  • 原文地址：https://www.cnblogs.com/benpaobadaniu/p/5100151.html
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