一直没有一个好的绘制视图的笔记，今天整理一下，分享给大家：
不多说，直接上代码。

一、核心绘图（C语言风格调用函数）

- (void)drawRect:(CGRect)rect {
     //获取上下文环境（获取画板）
    CGContextRef context = UIGraphicsGetCurrentContext(); 
     //把画笔移动到起始点 
    CGContextMoveToPoint(context, 100, 100);
    CGContextAddLineToPoint(context, 250, 250);  
    CGContextAddLineToPoint(context, 150, 450);
    CGContextAddLineToPoint(context, 50, 300); 
    CGContextAddLineToPoint(context, 100, 100);   //设置描边的颜色    
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
     //描边
    CGContextStrokePath(context);
    //设置填充颜色
    CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
   //填充
   CGContextFillPath(context);
}

//drawRect:方法会在创建View的实例时，系统自动调用一次，绝对不可以手动调用该方法.

二、 贝塞尔曲线UIBezierPath 绘图

• 绘制曲线
  UIBezierPath *path = [UIBezierPath bezierPath];
  [path moveToPoint:CGPointMake(150, 50)];
  [path addCurveToPoint:CGPointMake(50, 150) controlPoint1:CGPointMake(50, 50) controlPoint2:CGPointMake(150, 150)];
  [path addCurveToPoint:CGPointMake(150, 250) controlPoint1:CGPointMake(150, 150) controlPoint2:CGPointMake(50, 250)];
  [[UIColor redColor]setStroke];
  [path stroke];
• 绘制矩形
  UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(20, 300, 200, 15)];
  path.lineWidth = 4;//描边线宽
  path.lineJoinStyle = kCGLineJoinBevel;//焦点的样式
  path.lineCapStyle = kCGLineCapSquare;//线两端的样式
  [[UIColor blueColor] setStroke];//设置描边色
  [path stroke];
• 绘制圆角矩形
  UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, 330, 200, 150) cornerRadius:75];
  [path stroke];
• 绘制椭圆
  UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(20, 330, 200, 150)];
  [[UIColor greenColor] setFill];//设置填充色
  [path fill];

三、 用bezierPath绘制八卦

  CGPoint center = CGPointMake(self.frame.size.width * 0.5, self.frame.size.height * 0.5);
  CGFloat radius = self.frame.size.width * 0.5 - 50;
  UIBezierPath *path = [UIBezierPath bezierPath];
  [path addArcWithCenter:center radius:radius startAngle:M_PI_2 * 3 endAngle:M_PI_2 clockwise:YES];  
  [path addCurveToPoint:CGPointMake(center.x , center.y - radius) controlPoint1:CGPointMake(center.x + radius , center.y) controlPoint2:CGPointMake(center.x - radius , center.y)]; 
  [[UIColor whiteColor] setStroke]; 
  [[UIColor blackColor] setFill];
  path.lineWidth = 5; 
  [path stroke];
  [path fill];
  UIBezierPath *path2 = [UIBezierPath bezierPath];
  [path2 addArcWithCenter:center radius:radius startAngle:M_PI_2  endAngle:M_PI_2* 3 clockwise:YES];  
  [path2 addCurveToPoint:CGPointMake(center.x , center.y + radius) controlPoint1:CGPointMake(center.x - radius , center.y) controlPoint2:CGPointMake(center.x + radius , center.y)];    
  [[UIColor blackColor] setStroke]; 
  [[UIColor whiteColor] setFill]; 
  path2.lineWidth = 5;
  [path2 stroke];
  [path2 fill];

四、绘制DownLoad图形

自定义UIView里的draw方法里
- (void)drawRect:(CGRect)rect {
CGPoint center = CGPointMake(self.frame.size.width * 0.5, self.frame.size.height * 0.5);
CGFloat radius = MIN(self.frame.size.width * 0.5, self.frame.size.height * 0.5) - 4;
UIBezierPath *bezierPath = [UIBezierPath bezierPath]；
[bezierPath addArcWithCenter:center radius:radius startAngle:M_PI_2 * 3 endAngle:M_PI_2 * 3 + M_PI * 2 * self.progressValue clockwise:YES];
bezierPath.lineWidth = 8;
[[UIColor blueColor]setFill];
[bezierPath fill];
}