UISCrollView —— 图片轮播器封装实现（三）——（第三讲）

1 #import <UIKit/UIKit.h>
2 
3 @interface XMGPageView : UIView
4 
5 + (instancetype)pageView;
6 
7 /** 所有需要展示的图片名称*/
8 @property (nonatomic, strong)NSArray *imageNames;
9 @end

#import "XMGPageView.h"

@interface XMGPageView ()<UIScrollViewDelegate>

@property (weak, nonatomic) IBOutlet UIScrollView *sc;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;

// 注意:NSTimer应该是weak
@property (weak, nonatomic) NSTimer *timer;
@end

@implementation XMGPageView


+ (instancetype)pageView
{
#warning 注意.这里有知识点
    return [[[NSBundle mainBundle] loadNibNamed:@"XMGPageView" owner:nil options:nil] lastObject];
}
/*
 自定义View的步骤:
 1.重写初始化方法 (在里面进行一次性的初始化)
    xib :awakeFromNib
    纯代码:initWithFrame
 2.重写layoutSubviews, 在里面布局子控件
 3.接收外界传入的数据, 重写set方法
*/

- (void)awakeFromNib
{
    
    self.sc.delegate = self;
    // 1.隐藏滚动条
    self.sc.showsHorizontalScrollIndicator = NO;
    self.sc.showsVerticalScrollIndicator = NO;
    
    // 2.设置UIScrollView的其它属性
    self.sc.bounces = NO;
    self.sc.pagingEnabled = YES;
    
    // 3.监听PageControl的点击事件
    [self.pageControl addTarget:self action:@selector(pageControlClick:) forControlEvents:UIControlEventValueChanged];
    
    // 4.通过KVC给UIPageControl的私有属性赋值, 设置自定义图片
    [self.pageControl setValue:[UIImage imageNamed:@"current"] forKeyPath:@"_currentPageImage"];
    [self.pageControl setValue:[UIImage imageNamed:@"other"] forKeyPath:@"_pageImage"];
    
    // 5.让UIScrollView每隔一段事件就切换一页
    [self startTimer];
}

#pragma mark - 内部监听
- (IBAction)pageControlClick:(UIPageControl *)sender
{
    
    self.sc.contentOffset = CGPointMake(sender.currentPage * self.sc.frame.size.width , 0);
}

#pragma mark - 定时器相关
- (void)startTimer
{
    // 打开定时器
    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextPage:) userInfo:@"lnj" repeats:YES];
    
    // 主线程在处理其它事件的时候, 分一点时间来处理NSTimer
    [[NSRunLoop mainRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}

// 切换到下一页
- (void)nextPage:(NSTimer *)timer
{
    // 1.获取下一页的页码
    NSUInteger page = self.pageControl.currentPage + 1;
    // 2.判断页码是否越界
    if (page >= _imageNames.count) {
        // 如果越界就回到第0页
        self.pageControl.currentPage = 0;
    }else
    {
        // 如果没有越界, 就进入到下一页
        self.pageControl.currentPage = page;
    }
    
    [self pageControlClick:self.pageControl];
}

- (void)stopTimer
{
    // 关掉定时器
    [self.timer invalidate];
}

#pragma mark - UIScrollViewDelegate
// 只要滚动就会调用
- (void)scrollViewDidScroll:(nonnull UIScrollView *)scrollView
{
    // 1.计算页码
    // 当前页码 = 偏移位 / UIScrollView的宽度
    CGFloat page = scrollView.contentOffset.x / scrollView.frame.size.width;
    int currnetPage = page + 0.5;
    
    // 2.修改页码
    self.pageControl.currentPage = currnetPage;
}

// 开始拖拽
- (void)scrollViewWillBeginDragging:(nonnull UIScrollView *)scrollView
{
    [self stopTimer];
}

// 结束拖拽
- (void)scrollViewDidEndDragging:(nonnull UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    [self startTimer];
    
}


- (void)setImageNames:(NSArray *)imageNames
{
    _imageNames = imageNames;
    
    // 0.每次重新设置图片, 都需要情空以前的图片
    for (UIView *subView in self.sc.subviews) {
        [subView removeFromSuperview];
    }
    
    // 1.创建图片

    // 1.初始化子控件, 添加图片
    for (int i = 0; i < _imageNames.count; i++) {
        
        // 1.创建UIImageView
        UIImageView *iv = [[UIImageView alloc] init];
        
        // 2.创建图片
        NSString *imageName = _imageNames[i];
        UIImage *image = [UIImage imageNamed:imageName];
        iv.image = image;

        // 4.添加到父控件
        [self.sc addSubview:iv];
    }
    
    // 2.设置pageControl的页码数量
    self.pageControl.numberOfPages = _imageNames.count;
    
}

- (void)layoutSubviews
{
    [super layoutSubviews];
    
    CGFloat width = self.sc.frame.size.width;
    CGFloat height = self.sc.frame.size.height;
    NSUInteger imageCount = self.imageNames.count;
    // 1.设置每个UIImageView的frame
    for (int i = 0; i < imageCount; i++) {
        UIImageView *iv = self.sc.subviews[i];
        iv.frame = CGRectMake(i * width, 0, width, height);
    }

    // 2.设置滚动范围
    self.sc.contentSize = CGSizeMake(imageCount * width, height);
}

@end

 1 #import "ViewController.h"
 2 #import "XMGPageView.h"
 3 
 4 @interface ViewController ()<UIScrollViewDelegate>
 5 
 6 @property(nonatomic, strong)XMGPageView *pageView;
 7 @end
 8 
 9 @implementation ViewController
10 
11 - (void)viewDidLoad
12 {
13     [super viewDidLoad];
14     /*
15      1.利用UIScrollView实现商品展示
16      2.用纯代码封装图片轮播器
17      */
18    
19     // 1.创建图片轮播器
20     XMGPageView *pageView = [XMGPageView pageView];
21     // 2.设置图片轮播器的frame
22     pageView.imageNames = @[@"img_01", @"img_02", @"img_03", @"img_04", @"img_05"];
23     pageView.frame = CGRectMake(27, 97, 320, 128);
24 //    pageView.frame = CGRectMake(0, 97, 330, 200);
25     [self.view addSubview:pageView];
26     self.pageView = pageView;
27     
28 }
29 
30 - (void)touchesBegan:(nonnull NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event
31 {
32     // 切换图片轮播器上的图片
33     self.pageView.imageNames = @[@"img_04", @"img_05"];
34 
35 }