block代替協議自定義UIScrollView實現分頁效果

#import <UIKit/UIKit.h>

@interface CustomScrollView : UIView
//頁數
@property (nonatomic, strong) NSInteger (^numberOfPageInScrollView)(CustomScrollView*scrollView);
//返回一個View,這裏顯示圖片，當前頁面
@property (nonatomic, strong) UIView *(^scroll)(CustomScrollView *scrollView,NSInteger page);
//點擊取得當前頁面
@property (nonatomic, strong) void (^didSelectAtPage)(CustomScrollView *scrollView,NSInteger page);
//當前頁
@property (nonatomic, assign) NSInteger currentPage;
//加載頁數，圖片等數據
- (void)reloadData;

@end

#import "CustomScrollView.h"

@interface CustomScrollView () <UIScrollViewDelegate>
{
    UIScrollView *_scrollView;
    NSInteger _currentPage;
}
@end

@implementation CustomScrollView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        
        _scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];
        _scrollView.pagingEnabled = YES;//設置能翻頁
        _scrollView.delegate = self;
        _scrollView.showsHorizontalScrollIndicator = NO;//鎖定只能水平滑動
        [self addSubview:_scrollView];
        //增加一個點擊手勢，用來獲得點擊view得到響應
        UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(didTap:)];
        [self addGestureRecognizer:tap];
    }
    return self;
}
//加載數據
- (void)reloadData
{
    //得到頁數
    NSInteger count = _numberOfPageInScrollView(self);
    CGFloat width = self.frame.size.width;//寬度
    CGFloat height = self.frame.size.height;//高度
    _scrollView.contentSize = CGSizeMake(width * count, height);//設置內容寬度和高度
    //生成對應頁數的view
    for (NSInteger i = 0; i < count; i++) {
        UIView *view = _scroll(self,i);
        view.frame = CGRectMake(i * width, 0, width, height);
    
        [_scrollView addSubview:view];
    }
}

- (void)didTap:(NSInteger)page
{
    NSInteger index = _scrollView.contentOffset.x / _scrollView.frame.size.width;
    _didSelectAtPage(self,index);
    //提示窗口
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"當前頁"
                                                    message:[NSString stringWithFormat:@"%d",index]
                                                    delegate:self
                                          cancelButtonTitle:@"cance"
                                          otherButtonTitles: nil];
    [alert show];
}

- (NSInteger)currentPage
{
    
    return  _scrollView.contentOffset.x / _scrollView.frame.size.width;
}

- (void)setCurrentPage:(NSInteger)currentPage
{
    _scrollView.contentOffset = CGPointMake(_scrollView.frame.size.width * currentPage, 0);
    _currentPage = currentPage;
    
}
//滑動後鬆開手指速度爲0時執行
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    NSInteger index = _scrollView.contentOffset.x / _scrollView.frame.size.width;
    //點擊的是那一頁
    _didSelectAtPage(self,index);
}




@end

#import "ViewController.h"
#import "CustomScrollView.h"
#import "UIImageView+WebCache.h"

@interface ViewController ()

@end

@implementation ViewController
            
- (void)viewDidLoad {
    [super viewDidLoad];
    CustomScrollView *scrollView = [[CustomScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 180)];
    scrollView.currentPage = 9;
    [self.view addSubview:scrollView];
    //設置滾動頁面
    scrollView.numberOfPageInScrollView = ^(CustomScrollView *add){
        return 10;
    };

    scrollView.scroll = ^(CustomScrollView *as,NSInteger page){
        UIImageView *imageView = [[UIImageView alloc] init];
        imageView.image = [UIImage imageNamed:@"1.jpg"];
        UILabel*label1 = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, 100, 30)];
        label1.text = [NSString stringWithFormat:@"Page :%d",page];

        if (page%2) {
            label1.backgroundColor = [UIColor magentaColor];
        }
        //在block裏不能用scrollView來調用
        //變量名字不好取
        as.didSelectAtPage = ^(CustomScrollView *as,NSInteger inte)
        {
            NSLog(@"%d",page);
        };

        [imageView addSubview:label1];
        return imageView;
    };
//怎麼自動調用是個問題
    [scrollView reloadData];

}

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

@end