滾動視圖

1. 滾動視圖的基本使用

實例: 瀏覽大尺寸圖片

//  實例: 如何使用滾動實現顯示大圖片
    
    UIImage *image = [UIImage imageNamed:@"1001.jpg"];
    //  11000x5600
    NSLog(@"%f %f",image.size.width,image.size.height);
    
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 11000, 5600)];
    imageView.image = image;
    //[self.view addSubview:imageView];
    
    //創建UIScrollView滾動視圖
    //注意: 滾動視圖其實應該有兩個大小, 本身大小, 內容大小
    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
    //再去設置內容的大小
    scrollView.contentSize = CGSizeMake(11000, 5600);
    
    [scrollView addSubview:imageView];
    [self.view addSubview:scrollView];
    
    
    //常用的設置
    //是否顯示水平方向滾動提示條
    scrollView.showsHorizontalScrollIndicator = NO;
    //是否顯示豎直方向滾動提示條
    scrollView.showsVerticalScrollIndicator = NO;
    //去掉反彈效果
    scrollView.bounces = NO;

2.滾動視圖的基本原理 + 滾動視圖的事件處理

3.滾動視圖的縮放

4.項目常用: 新手引導界面(UIPageControl)
詳細實戰:

    [self createScrollView];
    
    [self createPageControl];
}
-(void)createPageControl
{
    CGSize size = self.view.frame.size;
    _pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, 0, 100, 20)];
    _pageControl.center = CGPointMake(size.width/2, size.height - 40);
    _pageControl.numberOfPages = 4;
    [self.view addSubview:_pageControl];
    
    //注意事件類型
    [_pageControl addTarget:self action:@selector(dealPage:) forControlEvents:UIControlEventValueChanged];
    
}
-(void)dealPage:(UIPageControl *)pc
{
    //把序號轉化為滾動視圖x的偏移
    double x = _scrollView.frame.size.width * pc.currentPage;
    
    [_scrollView setContentOffset:CGPointMake(x, 0) animated:YES];
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    int index = scrollView.contentOffset.x / scrollView.frame.size.width;
    _pageControl.currentPage = index;
}
-(void)createScrollView
{
    _scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    //分頁滾動
    _scrollView.pagingEnabled = YES;
    _scrollView.bounces = NO;
    _scrollView.showsHorizontalScrollIndicator = NO;
    _scrollView.delegate = self;
    [self.view addSubview:_scrollView];
    
    double w = _scrollView.frame.size.width;
    double h = _scrollView.frame.size.height;
    for (int i=0; i<4; i++) {
        
        UIImageView *back = [[UIImageView alloc] initWithFrame:CGRectMake(w*i, 0, w, h)];
        back.image = [UIImage imageNamed:@"guide_bg.png"];
        [_scrollView addSubview:back];
        
        NSString *name = [NSString stringWithFormat:@"guideView_%d.png",i+1];
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(w*i, 0, w, h)];
        imageView.image = [UIImage imageNamed:name];
        [_scrollView addSubview:imageView];
    }
    //設置內容大小
    _scrollView.contentSize = CGSizeMake(w * 4, h);


}