大致步骤

1) 新建一个UIView的子类(@interface HypnosisView : UIView)

2) 自定义绘图函数：(void) drawRect:(CGRect)rect

◆确定绘图范围：CGRect bounds=[self bounds]

◆获得CGContext, CGContextRef context=UIGraphicsGetCurrentContext();

◆进行绘图操作

3) 将新视图绑定到主窗口

◆在HypnosisterAppDelegate中添加一个成员变量HypnosisView *view;

◆确定绘图范围

◆在didFinishLaunchingWithOptions中增加子视图:[_window addSubview:view];

◆进行显示 [_window makeKeyAndVisible];

待确定事项：

1) CGContextStrokePath的功能

2) makeKeyAndVisible消息的功能

关键代码如下：

Java代码

1) 绑定处理：

-(BOOL)application:(UIApplication*)applicationdidFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{
NSLog(@"didFinishLaunchingWithOptions.");
CGRectdrawingArea=[_windowbounds];
view=[[HypnosisViewalloc]initWithFrame:drawingArea];
[viewsetBackgroundColor:[UIColoryellowColor]];
[_windowaddSubview:view];
//Overridepointforcustomizationafterapplicationlaunch.
[_windowmakeKeyAndVisible];
returnYES;
}

2) 绘图处理：

-(void)drawRect:(CGRect)rect
{
NSLog(@"EnteringthedrawingfunctionofHyponsisView.");
//Getthedrawingrectangle
CGRectbounds=[selfbounds];
//Calculatethereferences
CGPointcenter;
center.x=bounds.origin.x+bounds.size.width/2.0;
center.y=bounds.origin.y+bounds.size.height/2.0;
floatradius=hypot(bounds.size.width,bounds.size.height)/2.0;
//PrepareDrawing
CGContextRefcontext=UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context,10);
[[UIColorgreenColor]setStroke];
//Drawingthecircles
for(floatr=radius;r>0;rr=r-25)
{
CGContextAddArc(context,center.x,center.y,r,0.0,M_PI*2.0,YES);
CGContextStrokePath(context);
}
}

运行效果：