How to draw an Arc using core draw - ios

Question

I want to draw an arc like in the following figure using core draw.
Not exactly same but I have background images set. I need to draw arc based on the file download. Now the percentage of download number I have. How can I do it using core draw?

Answer 1

The image above are just two circles - one is cutting a hole in another. This is not near to what you want to accomplish.
You need to use CGContextAddArc.
Do something like this:
open a path
move to a point
start drawing the Arc with CGContextAddArc
move (and draw a line) inwards to the arc center the desired width of the slice
draw an backward arc
close the path

Answer 2

Use Mid point Algorithm, If you want to draw circles , to make concentric circle provide difference in radius of your circles

Answer 3

I have what you want:
// CircularProgress.h
#import <UIKit/UIKit.h>
#interface CircularProgress : UIView
#property (nonatomic, assign) CGFloat percent;
#end
// CircularProgress.m
#import "CircularProgress.h"
#implementation CircularProgress
- (void)setPercent:(CGFloat)percent
{
_percent = percent;
[self setNeedsDisplay];
}
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect bounds = [self bounds];
CGPoint center = CGPointMake(bounds.size.width / 2.0, bounds.size.height / 2.0);
CGFloat lineWidth = 8.0;
CGFloat innerRadius = (bounds.size.width / 2.0) - lineWidth;
CGFloat outerRadius = innerRadius + lineWidth;
CGFloat startAngle = -((float)M_PI / 2.0);
CGFloat endAngle = ((self.percent / 100.0) * 2 * (float)M_PI) + startAngle;
UIBezierPath *processBackgroundPath = [UIBezierPath bezierPath];
processBackgroundPath.lineWidth = lineWidth;
CGFloat radius = (self.bounds.size.width - lineWidth) / 2.0;
CGFloat fullAngle = (2.0 * (float)M_PI) + startAngle;
[processBackgroundPath addArcWithCenter:center radius:radius startAngle:startAngle endAngle:fullAngle clockwise:YES];
[[UIColor whiteColor] set];
[processBackgroundPath stroke];
CGMutablePathRef progressPath = CGPathCreateMutable();
CGPathMoveToPoint(progressPath, NULL, center.x, center.y - innerRadius);
CGPathAddArc(progressPath, NULL, center.x, center.y, innerRadius, startAngle, endAngle, YES);
CGPathAddArc(progressPath, NULL, center.x, center.y, outerRadius, endAngle, startAngle, NO);
CGPathCloseSubpath(progressPath);
UIColor *aColor = [UIColor colorWithRed:0.941 green:0.776 blue:0.216 alpha:1.0];
[aColor setFill];
CGContextAddPath(context, progressPath);
CGContextFillPath(context);
CGPathRelease(progressPath);
}
#end
You just need to create an object of CircularProgress class of the desired size (it should be square) and add it as subview to your main view. Then simply change the percent value and enjoy result. The color and width are hardcoded for now because it's not the finished control but you should catch the idea.