iOS贝塞尔曲线画返回箭头

UIImageView  *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];

    imageView.backgroundColor = [UIColor redColor];
    [self.view addSubview:imageView];
// 线的路径
    UIBezierPath *polygonPath = [UIBezierPath bezierPath];
    
    // 这些点的位置都是相对于所在视图的
    // 起点
    [polygonPath moveToPoint:CGPointMake(25, 5)];
    // 其他点
    [polygonPath addLineToPoint:CGPointMake(15, 15)];
    [polygonPath addLineToPoint:CGPointMake(25, 25)];
    
//    [polygonPath closePath]; // 添加一个结尾点和起点相同
    
    CAShapeLayer *polygonLayer = [CAShapeLayer layer];
    polygonLayer.lineWidth = 3;
    polygonLayer.strokeColor = [UIColor whiteColor].CGColor;
    polygonLayer.path = polygonPath.CGPath;
    polygonLayer.fillColor = nil; // 默认为blackColor
    [imageView.layer addSublayer:polygonLayer];

参考链接:https://www.cnblogs.com/jaesun/p/iOS-CAShapeLayerUIBezierPath-hua-xian.html