drawing.m

    NSArray *food = @[
                      @{
                          @"name" : @"滄州燒臘",
                          @"score" : @"50"
                          },
                      @{
                          @"name" : @"Subway",
                          @"score" : @"80"
                          },
                      @{
                          @"name" : @"鐵板城",
                          @"score" : @"70"
                          },
                      ];
    int totalScore = 0;
    for (int i=0; i<[food count]; i++) {
        int foodScore = [food[i][@"score"] intValue];
        totalScore += foodScore;
    }
    
    
    CGFloat lastAngle = 0;
    UIGraphicsBeginImageContext(CGSizeMake(200, 200));
    for (int i=0; i<[food count]; i++) {
        CGFloat hue = (CGFloat)arc4random_uniform(256) / 256.0;  //  0.0 to 1.0
        CGFloat saturation = ( (CGFloat)arc4random_uniform(128) / 256.0 ) + 0.5;  //  0.5 to 1.0, away from white
        CGFloat brightness = ( (CGFloat)arc4random_uniform(128) / 256.0 ) + 0.5;  //  0.5 to 1.0, away from black
        UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
        [color setFill];
        
        int foodScore = [food[i][@"score"] intValue];
        CGFloat angle = M_PI * 2 * foodScore / totalScore;
        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(100, 100) radius:100 startAngle:lastAngle endAngle:angle + lastAngle clockwise:YES];
        [path addLineToPoint:CGPointMake(100, 100)];
        [path closePath];
        [path fill];
        
        CGPoint smallerCirclePoint = CGPointMake(100 + 50 * cos(lastAngle + angle / 2), 100 + 50 * sin(lastAngle + angle / 2));
        NSString *foodName = food[i][@"name"];
        [foodName drawAtPoint:smallerCirclePoint withAttributes:@{
             NSForegroundColorAttributeName : [UIColor blackColor]
                                                                  }];

        lastAngle = angle + lastAngle;

    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
    imageView.center = self.view.center;
    [self.view addSubview:imageView];