在iOS中，图形的绘制是基于UIView来绘制的，所以，我们要先创建一个用来绘制图形的UIView类。
UIView的类中有一个方法是专门用来绘制图形的：
/* // Only override drawRect: if you perform custom drawing. // An empty implementation adversely affects performance during animation. - (void)drawRect:(CGRect)rect { // Drawing code } */ 我尝试了一些简单的图形绘制命令： /* // Only override drawRect: if you perform custom drawing. // An empty implementation adversely affects performance during animation. */ - (void)drawRect:(CGRect)rect { // Drawing code //获取当前设备的上下文（画布） CGContextRef context = UIGraphicsGetCurrentContext(); //画笔移到某一点 CGContextMoveToPoint(context, 0, 0); //从一点到某一点画条线 CGContextAddLineToPoint(context, 100, 100); //给线渲染涂色 CGContextStrokePath(context); //矩形框 CGContextAddRect(context, CGRectMake(0, 0, 100, 100)); CGContextStrokeRect(context, CGRectMake(0, 0, 100, 100)); //实心矩形 CGContextFillRect(context, CGRectMake(100, 100, 100, 100)); //空心圆 CGContextStrokeEllipseInRect(context, CGRectMake(100, 200, 100, 100)); //实心圆 CGContextFillEllipseInRect(context, CGRectMake(100, 300, 100, 100)); //绘制文字 NSString * str = @"Hello world!"; [str drawAtPoint:CGPointMake(125, 400) withAttributes:nil]; //绘制图片 [img drawAtPoint:CGPointMake(100, 500)]; [img drawAsPatternInRect:CGRectMake(100, 400, 50, 50)]; //平铺填充 CGContextDrawImage(context, CGRectMake(100, 500, 80, 80), [img CGImage]);//自由缩放 } 效果看起来笨笨的，哈哈，继续学习ing
