UIBezierPath cannot draw a perfect circle

Question

I'm using UIBezierPath to draw a circle like

UIBezierPath *outerPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(heigth/2.0f, heigth/2.0f)
                                                             radius:(self.frame.size.height * 0.5)
                                                         startAngle:DEGREES_TO_RADIANS(-90)
                                                           endAngle:DEGREES_TO_RADIANS(270)
                                                          clockwise:YES];
outerCircleLayer = [CAShapeLayer layer];

outerCircleLayer.lineCap = kCALineCapRound;
outerCircleLayer.lineWidth = 1.0f;
outerCircleLayer.strokeColor = HexRGB(0x4cae7b).CGColor;
outerCircleLayer.fillColor = [[UIColor clearColor] CGColor];
outerCircleLayer.path = outerPath.CGPath;
outerCircleLayer.strokeEnd = 0;

but I found the circle is not perfect,just like below

enter image description here

How can I do?

Updated:

Update a pic,from here we can find the start point and the end point are not smooth. enter image description here

What's the problem with the circles? (the image quality is so low that I can't tell if there is a problem with the shape or the angle or anything else) — David Rönnqvist
@DavidRönnqvist it's easier to find the problem when increasing the scale,just like the same problem as stackoverflow.com/questions/29063680/… — Rick

Sanjay Mohnani Sanjay Mohnani · Accepted Answer · 2015-05-27T10:43:35

While using CAShapeLayer to create a smooth circle you need to set the shouldRasterize and provide the rasterizationScale also. These are basically the attributes of CAShapeLayer.

layer = [CAShapeLayer layer];

// customize layer

// set shouldRasterize & rasterizationScale
layer.shouldRasterize = YES;
layer.rasterizationScale = [UIScreen mainScreen].scale;

UIBezierPath cannot draw a perfect circle

1 Answers