iOS画月亮

主要思路

1.CAShapeLayer + UIBezierPath

2.两个弧线的关系是个数学问题

我的实现是，月亮的两个端点连线作为内弧的圆半径，但感觉不是很漂亮，跟月亮实际有些偏离。希望有朋友有更好方法。

3.难点在计算，内弧圆的圆心和半径，画画图结合点数学基础就OK了。

//
//  ViewController.m
//  MoonProgressDemo
//
//  Created by Robin on 2019/8/4.
//  Copyright © 2019 RobinCompany. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) CAShapeLayer *moonLayer;
@property (nonatomic, assign) CGFloat progress;
@property (weak, nonatomic) IBOutlet UISlider *slider;

@end

@implementation ViewController

#define ScreenW CGRectGetWidth([UIScreen mainScreen].bounds)
#define ScreenH CGRectGetHeight([UIScreen mainScreen].bounds)

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self addLayer];
    _slider.layer.anchorPoint = CGPointMake(1, 1);
    _slider.transform = CGAffineTransformMakeRotation(- M_PI_2);
}

- (void)addLayer {
    CAShapeLayer *moon = [CAShapeLayer layer];
    CGFloat quardW = 0.25 * ScreenW;
    moon.frame = CGRectMake(quardW, 0.25 * ScreenH, 2 * quardW, 2 * quardW);
    _moonLayer = moon;
//    _moonLayer.backgroundColor = [UIColor redColor].CGColor;
    [self.view.layer addSublayer:moon];
    moon.strokeColor = [UIColor redColor].CGColor;
    moon.fillColor = nil;
    CGFloat x0 = 0.5 * CGRectGetWidth(_moonLayer.bounds);
    CGFloat y0 = 0.5 * CGRectGetHeight(_moonLayer.bounds);
    
    CGPoint center = CGPointMake(x0, y0);
    CGFloat radius = 0.5 * CGRectGetWidth(_moonLayer.bounds);
    CGFloat startAngle = 0.f;
    CGFloat endAngle = - M_PI;
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES];
//    moon.path = path.CGPath;
    CGPoint center1 = CGPointMake(x0, y0 - radius / (tan(M_PI / 6.0f)));
    
    UIBezierPath *path1 = [UIBezierPath bezierPathWithArcCenter:center1 radius:2.0f * radius startAngle:2.0f * M_PI / 3.0f endAngle:M_PI / 3.0f clockwise:NO];
    
//    [path addArcWithCenter:center1 radius:2 * radius startAngle:4 * M_PI / 3 endAngle:5 * M_PI / 3 clockwise:NO];
    [path appendPath:path1];
    moon.path = path.CGPath;
    
}
- (IBAction)sliderSlide:(UISlider *)sender {
    self.progress = sender.value;
    _moonLayer.fillColor = [UIColor colorWithRed:0 green:0 blue:255 alpha:_progress].CGColor;
//    _moonLayer.anchorPoint
    _moonLayer.affineTransform = CGAffineTransformMakeRotation(_progress * M_PI / 6.0f);

}

- (void)setProgress:(CGFloat)progress {
    _progress = progress;
    CGFloat endAngle1 = (1.0f + progress) * M_PI;
    CGFloat x0 = 0.5 * CGRectGetWidth(_moonLayer.bounds);
    CGFloat y0 = 0.5 * CGRectGetHeight(_moonLayer.bounds);
    CGPoint center = CGPointMake(x0, y0);
    CGFloat radius = 0.5 * CGRectGetWidth(_moonLayer.bounds);
    UIBezierPath *path1 = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:0.f endAngle:endAngle1 clockwise:YES];
    
    CGFloat r2 = 2.0f * cos(0.5 * progress * M_PI) * radius;
    CGFloat startAngle2 = (0.5 * progress + 2.0f / 3.0f) * M_PI;
    CGFloat endAngle2 = (0.5 * progress + 1.0f / 3.0f) * M_PI;
    CGFloat distance = radius * sin (0.5 * progress *M_PI) + r2 * cos(M_PI / 6);
    CGFloat deltaX = distance * sin(0.5 * progress * M_PI);
    CGFloat deltaY = distance * cos(0.5 * progress * M_PI);
    CGPoint center2 = CGPointMake(x0 + deltaX, y0 - deltaY);
    UIBezierPath *path2 = [UIBezierPath bezierPathWithArcCenter:center2 radius:r2 startAngle:startAngle2 endAngle:endAngle2 clockwise:NO];
    [path1 appendPath:path2];
    _moonLayer.path = path1.CGPath;
}
@end