iOS中间透明周围不透明(镂空)方法实现特种进度条

前言

最近由于要给APP更新UI，然后UIDesigner为了"尝鲜",给我一些新的界面设计，所以我这里也不得不再来造些另外的轮子。如果对您有帮助，麻烦Github给个star

如果有兴趣的，可以移步iOS UIBezierPath绘图相关问题,里边一些遇到的问题的详细的总结

这里先来看下今天要造的轮子

效果图

没错，就是上边的进度条。

实现

• 先说下思路（采用的是使用MASK遮罩，然后改变底层OrangeColorLayer长度，以达到进度条长度变化的思路）
  1. 首先，我们创建一个新的类，继承自UIView,然后，我们采用Core Graphics框架和UIBezierPath类来实现中间的进度条样式。先来分析下进度条，可以看出来，进度条内部，有两种颜色：橙色的TintColor，DarkGray的进度达不到的进度条颜色，然后，进度条背景色lightDarkColor,和最上层圆形中的小圆点。
  2. 我这里的进度条，实现发方法是采用4层layer来实现：最底层，绘制DarkGray颜色的进度条，再往上一层，设置有颜色的一层layer,通过改变该层layer的宽度，已达到有颜色进度条的长度变化，再上层，是一个中间进度条轮廓透明，周围是lightGrayColor背景色的遮罩View,最上层，是几个进度条内部小圆的layer。采用的是使用MASK遮罩，然后改变底层OrangeColorLayer长度，以达到进度条长度变化的思路

• 这里代码
  1.先看下暴露出来的API接口
  ```
  @interface RRMyMaterialProgressBar : UIView
  //一共项数
  //@property (nonatomic,assign) CGFloat totalStepsCounts;

  @property (nonatomic,strong) CAShapeLayer *firstArc;
  
  @property (nonatomic,strong) CAShapeLayer *secondArc;
  
  @property (nonatomic,strong) CAShapeLayer *thirdArc;
  
  @property (nonatomic,strong) CAShapeLayer *forthArc;
  
  //当前进度
  @property (nonatomic,assign) CGFloat currentPercentage;
  //渲染颜色
  //@property (nonatomic,strong) UIColor *progressBarTintColor;
  
  - (instancetype)initWithFrame:(CGRect)frame totalStepsCounts:(CGFloat)steps progressBarTintColor:(UIColor *)tintClr;
  
  @end
        ```          
  

PS：

这里是有一些问题的，最开始的时候，我是在drawRect方法中实现的，然后把总共的圆形个数，和进度条的渲染颜色都作为了外部属性，也是能实现的，但是：有些问题：考虑下我们的使用场景：一般我们都是在外层VC的viewWillAppear或者viewDidLoad方法中设置这个progressBar的进度，但是！如果在drawRect方法中实现的话，此时，内部的各个layer都还没有初始化，全部都是nil，如果在viewDidAppear方法中设置的话，会有一个BUG：刚进到页面内的时候，会看到进度条的进度是100%的，（因为默认创建ColorLayer的时候是设置的整个Frame的）,然后，调用外层viewDidAppear方法设置进度条的进度Layer长度，此时，进度条才会又从头开始显示。这么一来，用户体验就不是太好了。

所以，我又优化了一下：progressBarView 初始化的时候，就来绘制这些内层layer,以此来保证外部VC调用viewWillAppear或者viewDidLoad方法的时候，内层progressBar内的各个实例都已经ALLOC,并且可以设置他们。(所以，以前的totalStepsCounts和progressBarTintColor都可以设置为私有变量),然后我们直接在初始化方法中传入参数以赋值。

#import "RRMyMaterialProgressBar.h"

@interface RRMyMaterialProgressBar()

@property (nonatomic,strong) CALayer *backColorLayer;

@property (nonatomic,strong) CAShapeLayer *middleDarkArcLayer;

@property (nonatomic,strong) CAShapeLayer *foregroundMaskLayer;


//渲染颜色
@property (nonatomic,strong) UIColor *progressBarTintColor;

//上一次的比例
@property (nonatomic,assign) CGFloat lastPercentage;

//一共项数
@property (nonatomic,assign) CGFloat totalStepsCounts;

@end

@implementation RRMyMaterialProgressBar

- (instancetype)initWithFrame:(CGRect)frame totalStepsCounts:(CGFloat)steps progressBarTintColor:(UIColor *)tintClr{
    if (self == [super initWithFrame:frame]) {
        self.progressBarTintColor = tintClr;
        self.totalStepsCounts = steps;
        [self setupSubLayersWithFrame:frame];
    }
    return self;
}


- (void)setupSubLayersWithFrame:(CGRect)rect {
    self.layer.backgroundColor = [UIColor redColor].CGColor;
    
    //左右两侧的距离
    CGFloat padding = 10.f;
    //外圆的半径
    CGFloat arcRadius = 7.f;
    //中间线的线宽
    CGFloat middleLineWidth = 1.f;
    //内层圆按钮半径
    CGFloat innerArcRadius = 4.f;
    CGFloat viewWidth = rect.size.width;
    CGFloat viewHeight = rect.size.height;
    
    
    double arcSinValue = middleLineWidth/arcRadius;
    double radian = asin(arcSinValue);
    
    double tanValue = tan(radian);
    
    CGFloat arcTanLength = middleLineWidth/tanValue;
    
    CGFloat middleLineDistance = (viewWidth - 2 * padding - arcRadius * 2 - (self.totalStepsCounts * 2 - 2) * arcTanLength)/(self.totalStepsCounts - 1);
    
    
    self.middleDarkArcLayer = [CAShapeLayer layer];
    UIBezierPath *middleDrakColorPath = [UIBezierPath bezierPath];
    [middleDrakColorPath moveToPoint:CGPointMake(padding, viewHeight/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius, viewHeight/2) radius:arcRadius startAngle:M_PI endAngle:2*M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius +arcTanLength + middleLineDistance, viewHeight/2 - middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius +arcTanLength * 2 + middleLineDistance, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:2 * M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius + 3 * arcTanLength + middleLineDistance * 2, viewHeight/2 - middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius + 4 * arcTanLength + middleLineDistance * 2, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:2 * M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius + 5 * arcTanLength + middleLineDistance * 3, viewHeight/2 - middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius + 6 * arcTanLength + middleLineDistance * 3, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:3 * M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius + 5 * arcTanLength + middleLineDistance * 2, viewHeight/2 + middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius + 4 * arcTanLength + middleLineDistance * 2, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius + 3 * arcTanLength + middleLineDistance, viewHeight/2 + middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius + 2 * arcTanLength + middleLineDistance, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    [middleDrakColorPath addLineToPoint:CGPointMake(padding + arcRadius + arcTanLength, viewHeight/2 + middleLineWidth/2)];
    [middleDrakColorPath addArcWithCenter:CGPointMake(padding + arcRadius, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    [middleDrakColorPath closePath];
    
    self.middleDarkArcLayer.fillColor = RGB(203, 204, 205).CGColor;
    self.middleDarkArcLayer.path = middleDrakColorPath.CGPath;
    [self.layer addSublayer:self.middleDarkArcLayer];
    
    
    //MARK: 颜色层layer
    self.backColorLayer = [CALayer layer];
    self.backColorLayer.frame = CGRectMake(0, 0, viewWidth, viewHeight);
    self.backColorLayer.backgroundColor = self.progressBarTintColor.CGColor;
    self.backColorLayer.position = CGPointMake(0, viewHeight/2);
    self.backColorLayer.anchorPoint = CGPointMake(0, 0.5);
    [self.layer addSublayer:self.backColorLayer];
    
    
    self.foregroundMaskLayer = [CAShapeLayer layer];
    //MARK: 使用UIBezierPath 绘制遮挡VIEW的路径
    UIBezierPath *outerPath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0,0, rect.size.width, rect.size.height) cornerRadius:rect.size.height/2];
    
    UIBezierPath *colorPath = [UIBezierPath bezierPath];
    [colorPath moveToPoint:CGPointMake(padding, viewHeight/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius, viewHeight/2) radius:arcRadius startAngle:M_PI endAngle:2*M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius +arcTanLength + middleLineDistance, viewHeight/2 - middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius +arcTanLength * 2 + middleLineDistance, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:2 * M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius + 3 * arcTanLength + middleLineDistance * 2, viewHeight/2 - middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius + 4 * arcTanLength + middleLineDistance * 2, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:2 * M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius + 5 * arcTanLength + middleLineDistance * 3, viewHeight/2 - middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius + 6 * arcTanLength + middleLineDistance * 3, viewHeight/2) radius:arcRadius startAngle:M_PI + radian endAngle:3 * M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius + 5 * arcTanLength + middleLineDistance * 2, viewHeight/2 + middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius + 4 * arcTanLength + middleLineDistance * 2, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius + 3 * arcTanLength + middleLineDistance, viewHeight/2 + middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius + 2 * arcTanLength + middleLineDistance, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    [colorPath addLineToPoint:CGPointMake(padding + arcRadius + arcTanLength, viewHeight/2 + middleLineWidth/2)];
    [colorPath addArcWithCenter:CGPointMake(padding + arcRadius, viewHeight/2) radius:arcRadius startAngle:radian endAngle:M_PI - radian clockwise:YES];
    
    [outerPath appendPath:colorPath];
    [outerPath setUsesEvenOddFillRule:YES];
    
    
    self.foregroundMaskLayer.path = outerPath.CGPath;
    self.foregroundMaskLayer.fillRule = kCAFillRuleEvenOdd;
    self.foregroundMaskLayer.fillColor = RGB(221, 221, 221).CGColor;
    [self.layer addSublayer:self.foregroundMaskLayer];
    
    //MARK: 第一个内部圆
    self.firstArc = [CAShapeLayer layer];
    UIBezierPath *arcPath1 = [UIBezierPath bezierPath];
    [arcPath1 addArcWithCenter:CGPointMake(padding + arcRadius, viewHeight/2) radius:innerArcRadius startAngle:0 endAngle:2 * M_PI clockwise:1];
    self.firstArc.path = arcPath1.CGPath;
    self.firstArc.fillColor = RGB(221, 221, 221).CGColor;
    [self.layer addSublayer:self.firstArc];
    
    
    //MARK: 第二个内部圆
    self.secondArc = [CAShapeLayer layer];
    UIBezierPath *arcPath2 = [UIBezierPath bezierPath];
    [arcPath2 addArcWithCenter:CGPointMake(padding + arcRadius + arcTanLength + middleLineDistance + arcTanLength, viewHeight/2) radius:innerArcRadius startAngle:0 endAngle:2 * M_PI clockwise:1];
    self.secondArc.path = arcPath2.CGPath;
    self.secondArc.fillColor = RGB(221, 221, 221).CGColor;
    [self.layer addSublayer:self.secondArc];
    
    
    //MARK: 第三个内部圆
    self.thirdArc = [CAShapeLayer layer];
    UIBezierPath *arcPath3 = [UIBezierPath bezierPath];
    [arcPath3 addArcWithCenter:CGPointMake(padding + arcRadius + arcTanLength + middleLineDistance + arcTanLength + arcTanLength + middleLineDistance + arcTanLength, viewHeight/2) radius:innerArcRadius startAngle:0 endAngle:2 * M_PI clockwise:1];
    self.thirdArc.path = arcPath3.CGPath;
    self.thirdArc.fillColor = RGB(221, 221, 221).CGColor;
    [self.layer addSublayer:self.thirdArc];
    
    
    //MARK: 第四个内部圆
    self.forthArc = [CAShapeLayer layer];
    UIBezierPath *arcPath4 = [UIBezierPath bezierPath];
    [arcPath4 addArcWithCenter:CGPointMake(padding + arcRadius + arcTanLength + middleLineDistance + arcTanLength + arcTanLength + middleLineDistance + arcTanLength + arcTanLength + middleLineDistance + arcTanLength, viewHeight/2) radius:innerArcRadius startAngle:0 endAngle:2 * M_PI clockwise:1];
    self.forthArc.path = arcPath4.CGPath;
    self.forthArc.fillColor = RGB(221, 221, 221).CGColor;
    [self.layer addSublayer:self.forthArc];
}


- (void)setCurrentPercentage:(CGFloat)currentPercentage {
    _currentPercentage = currentPercentage;
    
    CABasicAnimation *animate = [CABasicAnimation animationWithKeyPath:@"transform.scale.x"];
    animate.fromValue = self.lastPercentage == 0 ? @(0) : @(self.lastPercentage);        
    animate.toValue = @(currentPercentage);
    animate.repeatCount = 1;
    animate.autoreverses = NO;
    animate.duration = 1.f;
    animate.removedOnCompletion = NO;
    animate.fillMode = kCAFillModeForwards;
    [self.backColorLayer addAnimation:animate forKey:@"progressAnimation"];
    
    self.lastPercentage = currentPercentage;

}

另外

整个进度条并不是圆形是环形的，如果有UI需求，我们可以通过设置API接口中的四个shapeLayer的fillColor值来改变内部小圆的颜色的

self.forthArc.fillColor = [UIColor yourWantedColor].CGColor;

这里有些参考资料
都是关于view中间镂空周围不是空的