If the content exceeds the size of the screen, the scrolling view is used to show the hidden part.
It can contain all other user interface elements such as image views, tags, text views, or even another scrolling view. ContentSize ContentInset ContentOffset Delegate In ViewController.h, add a scroll view and declare a scroll view to make the class conform to the delegate agreement, as shown below: Add a custom method addScrollView 注意： 我们必须添加一个命名为”AppleUSA1.jpg”到我们的项目，可以通过将图像拖到我们导航区域，其中列出了我们的项目文件所做的图像。图像应高于设备的高度。 Now when we run the application, we will see the following output. Once you scroll the view, you will be able to view the rest of the image:
In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress. 9.18.1. Important attribute ¶
An important method ¶
- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated
- (void)setContentOffset:(CGPoint)contentOffset animated:(BOOL)animated
9.18.2. An important delegation method ¶
#import -(void)addScrollView{
myScrollView = [[UIScrollView alloc]initWithFrame:
CGRectMake(20, 20, 280, 420)];
myScrollView.accessibilityActivationPoint = CGPointMake(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];
}
Implementing scrollView delegation in ViewController.m ¶
-(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");
}
Update viewDidLoad in ViewController.m, as shown below ¶
(void)viewDidLoad
{
[super viewDidLoad];
[self addScrollView];
//Do any additional setup after loading the view, typically from a nib
}
9.18.3. Output ¶
Principles, Technologies, and Methods of Geographic Information Systems
102