ios 中绘制图形

1、绘制梯形

-(void)drawRect:(CGRect)rect

{

  CGRect frameSize = self.frame;

  CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextMoveToPoint(context, 0, 30);//起始点

    CGContextAddLineToPoint (context, frameSize.size.width, 0);//上平行线

    CGContextAddLineToPoint (context, frameSize.size.width, frameSize.size.height);//右斜线

    CGContextAddLineToPoint (context, 0, frameSize.size.height);//下平行线

    CGContextClosePath(context);//收拢， 做成直角梯形

    [[UIColor redColor] setFill];

//    CGContextSetShadow(context, CGSizeMake(4, 3), 1);

    CGContextDrawPath(context, kCGPathFill);

}