1、可以用来画遮罩。自定义圆角
+ (instancetype)bezierPathWithRoundedRect:(CGRect)rect byRoundingCorners:(UIRectCorner)corners cornerRadii:(CGSize)cornerRadii;
UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];
view2.backgroundColor = [UIColor whiteColor];
view2.backgroundColor = [UIColor redColor];
[self.view addSubview:view2];
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft cornerRadii:CGSizeMake(0, 100)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = view2.bounds;
maskLayer.path = maskPath.CGPath;
view2.layer.mask = maskLayer;
2、绘制图形
（1）、drawRect方面里面直接构建路径然后 [aPath stroke]
-(void)drawRect:(CGRect)rect{
UIColor *color = [UIColor redColor];
[color set]; //设置线条颜色
UIColor *fillColor = [UIColor greenColor];
[fillColor setFill];
UIBezierPath* aPath = [UIBezierPath bezierPath];
aPath.lineWidth = 5.0;
aPath.lineCapStyle = kCGLineCapRound; //线条拐角
aPath.lineJoinStyle = kCGLineCapRound; //终点处理
// Set the starting point of the shape.
[aPath moveToPoint:CGPointMake(100.0, 0.0)];
// Draw the lines
[aPath addLineToPoint:CGPointMake(200.0, 40.0)];
[aPath addLineToPoint:CGPointMake(160, 140)];
[aPath addLineToPoint:CGPointMake(40.0, 140)];
[aPath addLineToPoint:CGPointMake(0.0, 40.0)];
[aPath closePath]; //第五条线通过调用closePath方法得到的
[aPath fill];
[aPath stroke]; //Draws line 根据坐标点连线
}
（2）、添加在view的layer层
UIBezierPath* aPath = [UIBezierPath bezierPath];
aPath.lineWidth = 5.0;
aPath.lineCapStyle = kCGLineCapRound; //线条拐角
aPath.lineJoinStyle = kCGLineCapRound; //终点处理
// Set the starting point of the shape.
[aPath moveToPoint:CGPointMake(100.0, 0.0)];
// Draw the lines
[aPath addLineToPoint:CGPointMake(200.0, 40.0)];
[aPath addLineToPoint:CGPointMake(160, 140)];
[aPath addLineToPoint:CGPointMake(40.0, 140)];
[aPath addLineToPoint:CGPointMake(0.0, 40.0)];
aPath.lineWidth = 2;
[aPath closePath]; //第五条线通过调用closePath方法得到的
[aPath fill];
[aPath stroke]; //Draws line 根据坐标点连线
CAShapeLayer *layer = [[CAShapeLayer alloc]init];
layer.path = aPath.CGPath;
layer.fillColor = [UIColor greenColor].CGColor;
layer.strokeColor = [UIColor redColor].CGColor;
[self.view.layer addSublayer:layer];
3、原生方法绘制图形
//创建一个椭圆的贝塞尔曲线 半径相等 就是圆了
UIBezierPath *mPath1 = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(60, 60, 10, 10)];
[mPath1 fill];
//创建一个矩形的贝塞尔线
UIBezierPath *mPath2 = [UIBezierPath bezierPathWithRect:CGRectMake(70,70, 10, 10)];
[mPath2 stroke];
//创建一个圆弧 传的弧度
UIBezierPath *mPath3 = [UIBezierPath bezierPathWithArcCenter:CGPointMake(50, 100)
radius:10
startAngle:DEGREES_TO_RADIANS(0)
endAngle:DEGREES_TO_RADIANS(180)
clockwise:YES];
[mPath3 fill];
//创建一个 矩形的贝塞尔曲线, 带圆角
UIBezierPath *mPath4 = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(250, 15, 20, 20) cornerRadius:3];
[mPath4 fill];
//定义一个矩形 边角会变成 设置的角度 方位/角度大小
UIBezierPath *mPath5 =[UIBezierPath bezierPathWithRoundedRect:CGRectMake(250, 45, 40, 40)
byRoundingCorners:UIRectCornerTopLeft
cornerRadii:CGSizeMake(10, 10)];
[mPath5 fill];
//定义一个二级的赛贝尔曲线 重点|拐弯点
UIBezierPath *mPath6 = [UIBezierPath bezierPath];
[mPath6 moveToPoint:CGPointMake(10,260)];
[mPath6 addQuadCurveToPoint:CGPointMake(200,260) controlPoint:CGPointMake(85, 240)];
[mPath6 setLineWidth:3];
[mPath6 stroke];
//定义一个三级的赛贝尔曲线 终点|拐点1|拐点2
UIBezierPath *mPath7 = [UIBezierPath bezierPath];
[mPath7 moveToPoint:CGPointMake(10,290)];
[mPath7 addCurveToPoint:CGPointMake(300, 290)
controlPoint1:CGPointMake(50, 270)
controlPoint2:CGPointMake(140, 340)];
[mPath7 stroke];