无法在CAShapeLayer上填写UIBezier

Question

我想在自定义视图中添加几个点，创建路径，关闭它并填充颜色。在for循环中，我水平放置几千个点并用线连接它们。但是，我无法画出近距离的bezier路径。问题是什么？

UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(0, screenHeight/2)];
 [path addLineToPoint:CGPointMake(0, screenHeight/2)];
[path addLineToPoint:CGPointMake(0, screenHeight/2)];

for (int i=0; i<=screenWidth; i+=screenWidth/stepNo) {
    [path addLineToPoint:CGPointMake(i, screenHeight/2)];
}
[path addLineToPoint:CGPointMake(screenWidth, screenHeight/2)];
[path addLineToPoint:CGPointMake(screenWidth, screenHeight)];
    [path addLineToPoint:CGPointMake(0, screenHeight)];

[path closePath];


//Create a CAShapeLayer that uses that UIBezierPath:
CAShapeLayer *shape = [CAShapeLayer layer];
shape.path = path.CGPath;
shape.fillColor = [UIColor colorWithRed:255/255.0 green:20/255.0 blue:147/255.0 alpha:1].CGColor;

// 5
[self.view.layer addSublayer:shape];