Filling Segmented Custom View

CustomView.h

//
//  FillingSegmentedCircleView.h
//  Created by Ben Norris on 2/20/15.
//  Copyright (c) 2015 BSN Design. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface FillingSegmentedCircleView : UIView

@property (nonatomic, assign) NSInteger segments;
@property (nonatomic, assign) double lineWidth;
@property (nonatomic, assign) double progress;

@end

CustomView.m

//
//  FillingSegmentedCircleView.m
//  Created by Ben Norris on 2/20/15.
//  Copyright (c) 2015 BSN Design. All rights reserved.
//

#import "FillingSegmentedCircleView.h"

@interface FillingSegmentedCircleView()

@property (nonatomic, strong) CAShapeLayer *backgroundRingLayer;
@property (nonatomic, strong) CAShapeLayer *ringLayer;

@end

@implementation FillingSegmentedCircleView

- (void)layoutSubviews {
    [super layoutSubviews];
    
    if (!self.backgroundRingLayer) {
        self.backgroundRingLayer = [CAShapeLayer layer];
        [self.layer addSublayer:self.backgroundRingLayer];
        
        CGRect rect = CGRectInset(self.bounds, self.lineWidth / 2.0, self.lineWidth / 2.0);
        UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:rect];
        
        self.backgroundRingLayer.path = path.CGPath;
        self.backgroundRingLayer.fillColor = nil;
        self.backgroundRingLayer.lineWidth = self.lineWidth;
        self.backgroundRingLayer.strokeColor = [UIColor blackColor].CGColor;
        self.backgroundRingLayer.lineDashPattern = [self getLineDashPatternForRect:self.bounds withSegments:self.segments];
    }
    self.backgroundRingLayer.frame = self.layer.bounds;
    
    if (!self.ringLayer) {
        self.ringLayer = [CAShapeLayer layer];
        
        CGRect innerRect = CGRectInset(self.bounds, self.lineWidth / 2.0, self.lineWidth / 2.0);
        UIBezierPath *innerPath = [UIBezierPath bezierPathWithOvalInRect:innerRect];
        
        self.ringLayer.path = innerPath.CGPath;
        self.ringLayer.fillColor = nil;
        self.ringLayer.lineWidth = self.lineWidth;
        self.ringLayer.strokeColor = [UIColor blueColor].CGColor;
        self.ringLayer.lineDashPattern = [self getLineDashPatternForRect:self.bounds withSegments:self.segments];
        self.ringLayer.anchorPoint = CGPointMake(0.5, 0.5);
        self.ringLayer.transform = CATransform3DRotate(self.ringLayer.transform, -M_PI/2, 0, 0, 1);
        
        [self.layer addSublayer:self.ringLayer];
    }
    self.ringLayer.frame = self.layer.bounds;
    
    [self updateLayerProperties];
}

- (NSArray *)getLineDashPatternForRect:(CGRect)rect withSegments:(NSUInteger)segments {
    CGFloat circumference = M_PI * rect.size.width;
    CGFloat segmentSpacing = 2.0;
    CGFloat totalSegmentSpacingLength = segmentSpacing * (segments);
    CGFloat segmentLength = (circumference - totalSegmentSpacingLength) / segments;
    
    return @[@(segmentLength), @(segmentSpacing)];
}

- (void)updateLayerProperties {
    if (self.ringLayer) {
        self.ringLayer.strokeEnd = self.progress;
    }
}

- (void)setProgress:(double)progress {
    _progress = progress;
    [self updateLayerProperties];
}

@end

Video Resource

https://developer.apple.com/videos/wwdc/2014/#411-video
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