以下类文件可帮我们用UIKit和QuartzCore框架来绘制向量图形。类似这个饼图（Pie Charts）。

// GraphView.h #import 
     
       @interface GraphView:UIView {
   } @end
     

// GraphView.m #import "GraphView.h" #define PI 3.14159265358979323846 static inline float radians(double degrees) { return degrees * PI / 180; } @implementation GraphView - (void)drawRect : (CGRect)rect {
      CGRect  parentViewBounds = self.bounds;    CGFloat  x = CGRectGetWidth(parentViewBounds) / 2;    CGFloat  y = CGRectGetHeight(parentViewBounds) * 0.55; // 获得图形上下文，然后清除之    CGContextRef ctx = UIGraphicsGetCurrentContext();    CGContextClearRect(ctx, rect); // 定义笔触颜色    CGContextSetRGBStrokeColor(ctx, 1, 1, 1, 1.0); // 定义线宽    CGContextSetLineWidth(ctx, 4.0); // 绘制饼图的一些必要值    double snapshotCapacity = 20; double rawCapacity = 100; double systemCapacity = 1; int offset = 5; double pie1_start = 315.0; double pie1_finish = snapshotCapacity * 360.0 / rawCapacity; double system_finish = systemCapacity * 360.0 / rawCapacity;      CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor greenColor] CGColor]));      CGContextMoveToPoint(ctx, x+2*offset, y);      CGContextAddArc(ctx, x+2*offset, y, 100, radians(snapshot_start), radians(snapshot_start+snapshot_finish), 0);      CGContextClosePath(ctx);      CGContextFillPath(ctx); // system capacity      CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor colorWithRed:15 green:165/255 blue:0 alpha:1] CGColor]));      CGContextMoveToPoint(ctx, x+offset, y);      CGContextAddArc(ctx, x+offset, y, 100, radians(snapshot_start+snapshot_finish+offset), radians(snapshot_start+snapshot_finish+system_finish), 0);      CGContextClosePath(ctx);      CGContextFillPath(ctx); // data capacity      CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor colorWithRed:99/255 green:184/255 blue:255/255 alpha:1] CGColor]));      CGContextMoveToPoint(ctx, x, y);      CGContextAddArc(ctx, x, y, 100, radians(snapshot_start+snapshot_finish+system_finish+offset), radians(snapshot_start), 0);      CGContextClosePath(ctx);      CGContextFillPath(ctx); }

代码中类似snapshot_start等变量值要在程序中设定好！！。

调用示例：

GraphView *graph = [[GraphView alloc] initWithFrame:CGRectMake(0.0, 20.0, 320.0, 460.0)]; [window addSubview:graph];