iOS - Scroll View(滚动视图)

使用Scroll View

滚动视图用于显示内容超过屏幕大小。它可以包含所有其他用户界面元素，如图像视图，标签，文本视图，甚至是另一个滚动视图本身。

重要的属性

• contentSize

• contentInset

• contentOffset

• delegate

重要的方法

- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated

- (void)setContentOffset:(CGzaixian)contentOffset animated:(BOOL)animated

重要的委托方法

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

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

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView

更新ViewController.h 如下：

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIScrollViewDelegate>
{
    UIScrollView *myScrollView;
}	

@end

添加一个自定义的方法addScrollView

-(void)addScrollView{
    myScrollView = [[UIScrollView alloc]initWithFrame:
    CGRectMake(20, 20, 280, 420)];
    myScrollView.accessibilityActivationzaixian = CGzaixianMake(100, 100);
    imgView = [[UIImageView alloc]initWithImage:
    [UIImage imageNamed:@"AppleUSA.jpg"]];
    [myScrollView addSubview:imgView];
    myScrollView.minimumZoomScale = 0.5;
    myScrollView.maximumZoomScale = 3;
    myScrollView.contentSize = CGSizeMake(imgView.frame.size.width,
    imgView.frame.size.height);
    myScrollView.delegate = self;
    [self.view addSubview:myScrollView];
}

注意事项：

我们必须命名为 “AppleUSA1.jpg”，我们可以通过拖动图像到我们的导航区域，项目文件列出的项目中添加图像。图像的分辨率高于设备看到的图像的滚动。

实现滚动视图在 ViewController.m 委托

-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return imgView;
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    NSLog(@"Did end decelerating");
}	
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
//    NSLog(@"Did scroll");
}
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView 
  willDecelerate:(BOOL)decelerate{
    NSLog(@"Did end dragging");
}
-(void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView{
    NSLog(@"Did begin decelerating");
}
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    NSLog(@"Did begin dragging");
}

更新 ViewController.m 中的 viewDidLoad 方法如下

(void)viewDidLoad
{
   [super viewDidLoad];
   [self addScrollView];
   //Do any additional setup after loading the view, typically from a nib
}

输出

现在，当我们运行程序时，我们会得到下面的输出。一旦滚动滚动视图，将能够看到图像的其余部分。