Custom View for iOS development

IOS developmentCustomViewIs the content to be introduced in this article, in the iOS SDKViewIs UIView, we can easily customizeView. Create a Window-based Application program and add a class named Hypnosister to it. This class inherits from UIObject. Modify this class to inherit from: UIView

 
 

  
  
@interface HypnosisView : UIView 
 
 

CustomViewThe key is to define the drawRect: method, because it is mainly changed by reloading this method.View. For example, you can use the following code to plot the effect of many rings.View.

 
 

  
  
View Code   
  
  
- (void)drawRect:(CGRect)rect   
  
  
{      
  
  
// What rectangle am I filling?    CGRect bounds = [self bounds];      
  
  
// Where is its center?    CGPoint center;      
  
  
center.x = bounds.origin.x + bounds.size.width / 2.0;      
  
  
center.y = bounds.origin.y + bounds.size.height / 2.0;      
  
  
// From the center how far out to a corner?    float maxRadius = hypot(bounds.size.width, bounds.size.height) / 2.0;      
  
  
// Get the context being drawn upon    CGContextRef context = UIGraphicsGetCurrentContext();      
  
  
// All lines will be drawn 10 points wide    CGContextSetLineWidth(context, 10);      
  
  
// Set the stroke color to light gray    [[UIColor lightGrayColor] setStroke];      
  
  
// Draw concentric circles from the outside in    for (float currentRadius = maxRadius; currentRadius > 0;   
  
  
currentRadius -= 20)    {          
  
  
CGContextAddArc(context, center.x, center.y,                          
  
  
                          currentRadius, 0.0, M_PI * 2.0, YES);         
  
  
 CGContextStrokePath(context);      
  
  
}  
  
  
} 
 
 

The view effect is as follows:

We can continue to draw something, such as drawing text, and add the following code after this method.

 
 

  
  
// Create a string NSString * text = @ "I am Zhu Yulin, not Zhu Qilin ";
  
  
// Get a font to draw it in UIFont * font = [UIFont boldSystemFontOfSize: 28];
  
  
// Where am I going to draw it? CGRect textRect;
  
  
TextRect. size = [text sizeWithFont: font];
  
  
TextRect. origin. x = center. x-textRect. size. width/2.0;
  
  
TextRect. origin. y = center. y-textRect. size. height/2.0;
  
  
// Set the fill color of the current context to black [[UIColor blackColor] setFill];
  
  
// Set the shadow to be offset 4 points right, 3 points down,
  
  
// Dark gray and with a blur radius of 2 points CGSize offset = CGSizeMake (4, 3 );
  
  
CGColorRef color = [[UIColor darkGrayColor] CGColor];
  
  
CGContextSetShadowWithColor (context, offset, 2.0, color );
  
  
// Draw the string [text drawInRect: textRect
  
  
WithFont: font];
 
 

Effect:

If the view is too large, we can place it in the middle of a UIScrollView, so that we can drag it. The relationship between UIScrollView and View is as follows:

Use the following code to create a View four times larger than the iPhone screen, and then use UIScrollView to display the View. The Code is as follows:

 
 

  
  
-(BOOL) application :( UIApplication *) application didfinishlaunchingwitexceptions :( NSDictionary *) launchOptions
  
  
{
  
  
// Create a CGRect of the form size
  
  
CGRect wholeWindow = [[self window] bounds];
  
  
// Create a form-sized HypnosisView instance
  
  
View = [[HypnosisView alloc] initWithFrame: wholeWindow];
  
  
UIScrollView * scrollView = [[UIScrollView alloc] initWithFrame: wholeWindow];
  
  
[[Self window] addSubview: scrollView];
  
  
// Make your view twice as large as the window CGRect reallyBigRect;
  
  
ReallyBigRect. origin = CGPointZero;
  
  
ReallyBigRect. size. width = wholeWindow. size. width * 2.0;
  
  
ReallyBigRect. size. height = wholeWindow. size. height * 2.0;
  
  
[ScrollView setContentSize: reallyBigRect. size];
  
  
CGPoint offset;
  
  
Offset. x = wholeWindow. size. width * 0.5;
  
  
Offset. y = wholeWindow. size. height * 0.5;
  
  
[ScrollView setContentOffset: offset];
  
  
// Create the view = [[HypnosisView alloc] initWithFrame: reallyBigRect];
  
  
[View setBackgroundColor: [UIColor clearColor];
  
  
[ScrollView addSubview: view];
  
  
[ScrollView release];
  
  
[[UIApplication sharedApplication] setStatusBarHidden: YES
  
  
WithAnimation: UIStatusBarAnimationFade];
  
  
[[Self window] makeKeyAndVisible];
  
  
Return YES;
  
  
}
 
 

In this way, we can drag to display invisible views, such:

With UIScrollView, we can also set the view scaling function to add the following code. In this way, we can use two fingers to scale the view.

 
 

  
  
// Enable zooming      
  
  
[scrollView setMinimumZoomScale:0.5];      
  
  
[scrollView setMaximumZoomScale:5];     
  
  
 [scrollView setDelegate:self]; 
 
 

Summary: DetailsIOS developmentCustomViewAfter the introduction, I briefly summarized the customViewI hope this article will be helpful to you! This article aims to make it easier for you to learnIOS developmentInView, Provides code download, address: http://files.cnblogs.com/zhuqil/Hypnosister.zip.