#import "ViewController.h"

#define kScreenW [UIScreen mainScreen].bounds.size.width
#define kScreenH [UIScreen mainScreen].bounds.size.height

#define kImgW (kScreenW-60)

@interface ViewController ()<UIScrollViewDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    /*_________ UIScrollView 滑动视图 ______________________________________________________*/
    //1⃣️创建
    
    UIScrollView *scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 20, kScreenW,kScreenW)];
    
    scrollView.backgroundColor = [UIColor lightGrayColor];
    
    [self.view addSubview:scrollView];
    
    //1.内容尺寸
    scrollView.contentSize = CGSizeMake(5 * kImgW, kScreenW);
    
    //5.是否开启首尾反弹效果 默认YES
        //滑动
    scrollView.bounces = YES;
    
    scrollView.delegate = self;

    //获取图片
    
    for (int i = 0; i<5; i++) {
        
        UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"scene%d.jpg",i+1]];
        
        UIImageView *imageV = [[UIImageView alloc]initWithFrame:CGRectMake(i * kImgW, 0, kImgW, kScreenW)];
        
        imageV.image = image;
        
        imageV.layer.borderColor = [[UIColor purpleColor]CGColor];
        
        //边框的宽度
        imageV.layer.borderWidth = 1;
        
        //圆角
        imageV.layer.cornerRadius = 30.0;
        
        //是否开启裁剪
        imageV.clipsToBounds = YES;
        
        [scrollView addSubview:imageV];
        
    }
    
    UIView *redView = [[UIView alloc]initWithFrame:CGRectMake(kScreenW/2, 0, 1, kScreenH)];
    
    redView.backgroundColor = [UIColor redColor];
    
    [self.view addSubview:redView];
    
    /*_______________________________________________________________*/
    
    
    //因为图片宽度比控件宽度短 为了让首位图片显示在控件中间 所以添加
    scrollView.contentInset = UIEdgeInsetsMake(0, 30, 0, 30);
    
    //滑动视图一开始显示 第一张图片就在中间
    scrollView.contentOffset = CGPointMake(-30, 0);
    


}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{

    [self customPage:scrollView];
    
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

    [self customPage:scrollView];
    
}

/**
 *  自定义的分页方法
 */
- (void)customPage:(UIScrollView *)scrollView{
    
    //1.获取当前偏移量 根据偏移量计算出应该显示的item的index
    
    NSInteger index = (scrollView.contentOffset.x + kImgW/2)/kImgW;
    
    NSLog(@"%ld",index);
    
    //2.通过index设置新的滑动偏移量
    
    //    scrollView.contentOffset = CGPointMake(index * kImgW, 0);
    
    [scrollView setContentOffset:CGPointMake(index * kImgW - 30.0, 0) animated:YES];

}
@end

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