iOS之OC源码，相册循环查看功能的实现

#import "ViewController.h"

#import "YZUIScrollView.h"

#define kuan ([UIScreen mainScreen].bounds.size.width+20)

#define gao [UIScreen mainScreen].bounds.size.height

@interface ViewController ()<UIScrollViewDelegate>

@property (weak, nonatomic) IBOutlet UIScrollView *huaBu;

@property(nonatomic,strong)NSArray *images;

@property(nonatomic)NSInteger currentIndex;

@end

@implementation ViewController

//懒加载,调用get方法时对属性进行初始化

-(NSArray *)images

{

    if(_images==nil)

    {

        NSMutableArray *imagearray=[NSMutableArray array];

        for (int i=1; i<7; i++) {

            NSString *imageName=[NSString stringWithFormat:@"new_feature_%d",i];

            UIImage *image=[UIImage imageNamed:imageName];

            [imagearray addObject:image];

        }

        _images=imagearray;

    }

    return _images;

}

- (void)viewDidLoad {

    [super viewDidLoad];

    //设置UIScrollView的contentSize

    _huaBu.contentSize=CGSizeMake(kuan*3, gao);

    //设置分页

    _huaBu.pagingEnabled=YES;

    //隐藏水平滚动栏和垂直滚动栏

    _huaBu.showsHorizontalScrollIndicator=NO;

    _huaBu.showsVerticalScrollIndicator=NO;

    //设置背景颜色,突出不同的图片

    _huaBu.backgroundColor=[UIColor blackColor];

    //设置代理要遵守协议<UIScrollViewDelegate>

    _huaBu.delegate=self;

    //调用方法添加子视图

    [self tianJiaZiShiTu];

    //调用方法添加图片

    [self tianJiaTuPian];

}

//添加子视图的方法

-(void)tianJiaZiShiTu

{

    //相册的话，是一个大的UIScrollView中放了很多的小UIScrollView，但是为了节省内存空间，所以只是添加了三个UIScrollView（图片不停的变换位置）

    for (int i=0; i<3; i++) {

        //创建YZUIScrollView

        YZUIScrollView * yzuisv=[[YZUIScrollView alloc] initWithFrame:CGRectMake(kuan*i, 0, kuan-20, gao)];

        //添加YZUIScrollView

        [_huaBu addSubview:yzuisv];

        //设置tag值，便于区分

        yzuisv.tag=1000+i;

    }

}

//添加方法的图片

-(void)tianJiaTuPian

{

    YZUIScrollView *leftSC=(YZUIScrollView *)[_huaBu viewWithTag:1000];

    YZUIScrollView *middleSC=(YZUIScrollView *)[_huaBu viewWithTag:1001];

    YZUIScrollView *rightSC=(YZUIScrollView *)[_huaBu viewWithTag:1002];

    leftSC.image=self.images[[self indexFofEnable:_currentIndex-1]];

    middleSC.image=self.images[[self indexFofEnable:_currentIndex]];

    rightSC.image=self.images[[self indexFofEnable:_currentIndex+1]];

    //设置偏移量，这步很重要

    _huaBu.contentOffset=CGPointMake(kuan, 0);

}

//确保索引可用

-(NSInteger)indexFofEnable:(NSInteger)index

{

    if(index<0)

    {

        return self.images.count-1;

    }

    else if (index>self.images.count-1)

    {

        return 0;

    }

    else

        return index;

}

//滚动结束后，把所有的缩放视图比例还原为1.0

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

{

    for (id obj in _huaBu.subviews) {

        if([obj isKindOfClass:[UIScrollView class]])

        {

            UIScrollView *scaleSC=(UIScrollView *)obj;

            scaleSC.zoomScale=1.0;

        }

    }

    //判断左右滑动

    //偏移量的x为0，就是说明向右滑动了，就是看的之前左边的那张图片

    if(scrollView.contentOffset.x==0)

    {

        //对应的图像应该是变成左边的图像

        _currentIndex--;

    }

    //偏移量的x为两个屏幕的宽，就是说明向左滑动了，就是看的之前右边的那张图片

    else if(scrollView.contentOffset.x== kuan*2)

    {

        //对应的图像应该是变成右边的图像

        _currentIndex++;

    }

    _currentIndex=[self indexFofEnable:_currentIndex];

    [self tianJiaTuPian];

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end

//第二个类

#import "YZUIScrollView.h"

@interface YZUIScrollView ()<UIScrollViewDelegate>

@property(nonatomic,strong)UIImageView *imageview;

@property(nonatomic,strong)UIImage *image;//内容视图的图片

@end

@implementation YZUIScrollView

-(instancetype)initWithFrame:(CGRect)frame

{

    if(self =[super initWithFrame:frame])

    {

        //添加内容视图

        UIImageView *imageview1=[[UIImageView alloc] initWithFrame:self.bounds];

        [self addSubview:imageview1];

        _imageview=imageview1;

        //设置最大最小倍数和代理

        self.minimumZoomScale=0.5;

        self.maximumZoomScale=1.5;

        self.delegate=self;

        //双击事件

        UITapGestureRecognizer *tap=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(shuangJi:)];

        tap.numberOfTapsRequired=2;

        [self addGestureRecognizer:tap];

    }

    return self;

}

-(void)shuangJi:(UITapGestureRecognizer *)tap

{

    //当缩放比例不为1.0，还原缩放比例

    if (self.zoomScale !=1.0) {

        [self setZoomScale:1.0 animated:YES];

        return ;

    }

    CGPoint location =[tap locationInView:self];

    CGRect rect =CGRectMake(location.x-100, location.y-100,200,200);

    [self zoomToRect:rect animated:YES];

}

//重写setImg方法

-(void)setImage:(UIImage *)image

{

    //set本身的方法要完成的事必须完成

    _image=image;

    //设置内容视图的图片

    _imageview.image=image;

}

//UIScrollViewDelegate代理方法

-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

{

    return _imageview;

}

@end