UI效果

实现的思路

就是通过贝塞尔曲线画出时间轴的圆环的路径，然后
使用CAShaper来渲染UI，再通过
animation.beginTime = [cilrclLayer convertTime:CACurrentMediaTime() fromLayer:nil] + circleTimeOffset 来设置每个圆环的动画开始时间，
，每个地方都是有两层layer的，一层是底部灰色样式的（即没有到达时候的颜色）一层是到达得阶段的颜色，
到达的layer在上面，如果要开启动画，我们就得先将
到达的layer隐藏掉，然后开始动画的时候，将对应的那一条展示，开启动画的时候将hidden置为NO，这时候，其实layer是展示不了的（不会整个展示），因为我们添加了strokeEnd的动画，他会随者动画的进行而逐渐展示，所以我们在动画代理方法animationDidStart中，将layer 设置为可见，（如果没有设置动画代理，也可以在添加动画的时候设置为可见）

代码

//
//  LBTimeView.m
//  LBTimeLine
//
//  Created by mac on 2024/6/9.
//#import "LBTimeView.h"
#define ScreenWidth [UIScreen mainScreen].bounds.size.width
#define RGB(r, g, b)    [UIColor colorWithRed:(r)/255.f green:(g)/255.f blue:(b)/255.f alpha:1.f]
#define SizeScale (([UIScreen mainScreen].bounds.size.width > 320) ? [UIScreen mainScreen].bounds.size.width/320 : 1)const float BETTWEEN_LABEL_OFFSET = 20;
const float LINE_WIDTH = 1.9;
const float CIRCLE_RADIUS = 3.7;
const float INITIAL_PROGRESS_CONTAINER_WIDTH = 20.0;
const float PROGRESS_VIEW_CONTAINER_LEFT = 51.0;
const float VIEW_WIDTH = 225.0;@interface LBTimeView ()
{CGPoint lastpoint;NSMutableArray *layers;NSMutableArray *circleLayers;int layerCounter;int circleCounter;CGFloat timeOffset;CGFloat leftWidth;CGFloat rightWidth;CGFloat viewWidth;
}@end@implementation LBTimeView-(id)initWithFrame:(CGRect)frame sum:(NSInteger)sum current:(NSInteger)current{self = [super initWithFrame:frame];if (self) {self.frame = frame;[self configureTimeLineWithNum:sum andCurrentNum:current];}return self;// Do any additional setup after loading the view, typically from a nib.
}- (void)configureTimeLineWithNum:(NSInteger)sum andCurrentNum:(NSInteger)currentStatus {// NSInteger  currentStatus = 3;circleLayers = [[NSMutableArray alloc] init];layers = [[NSMutableArray alloc] init];CGFloat U = (ScreenWidth - 80- sum+1)/(sum - 1);CGFloat betweenLineOffset = 0;//CGFloat totlaHeight = 8;// CGFloat yCenter = - 48 + (ScreenWidth - 248)/2;CGFloat yCenter = 40;// CGFloat xCenter;UIColor *strokeColor;CGPoint toPoint;CGPoint fromPoint;int i = 0;for (int j = 0;j < sum;j ++) {//configure circlestrokeColor = i < currentStatus ? RGB(224, 0, 30) : RGB(233, 233, 233);UIBezierPath *circle = [UIBezierPath bezierPath];[self configureBezierCircle:circle withCenterY:yCenter];CAShapeLayer *circleLayer = [self getLayerWithCircle:circle andStrokeColor:strokeColor];//[circleLayers addObject:circleLayer];//add static background gray circleCAShapeLayer *grayStaticCircleLayer = [self getLayerWithCircle:circle andStrokeColor:RGB(233, 233, 233)];[self.layer addSublayer:grayStaticCircleLayer];[self.layer addSublayer:circleLayer];//configure lineif (i > 0) {fromPoint = lastpoint;toPoint = CGPointMake(yCenter - CIRCLE_RADIUS,60*SizeScale);lastpoint = CGPointMake( yCenter + CIRCLE_RADIUS+ 1,60*SizeScale);UIBezierPath *line = [self getLineWithStartPoint:fromPoint endPoint:toPoint];CAShapeLayer *lineLayer = [self getLayerWithLine:line andStrokeColor:strokeColor];// CAShapeLayer *lineLayer2 = [self getLayerWithLine:line andStrokeColor:strokeColor];[layers addObject:lineLayer];//add static background gray lineCAShapeLayer *grayStaticLineLayer = [self getLayerWithLine:line andStrokeColor:RGB(233, 233, 233)];[self.layer addSublayer:grayStaticLineLayer];[self.layer addSublayer:lineLayer];} else {lastpoint = CGPointMake( yCenter + CIRCLE_RADIUS+1,60*SizeScale);}betweenLineOffset = BETTWEEN_LABEL_OFFSET;yCenter += U;i++;}
}- (CAShapeLayer *)getLayerWithLine:(UIBezierPath *)line andStrokeColor:(UIColor *)strokeColor {CAShapeLayer *lineLayer = [CAShapeLayer layer];lineLayer.path = line.CGPath;lineLayer.strokeColor = strokeColor.CGColor;lineLayer.fillColor = nil;lineLayer.lineWidth = 1.4;return lineLayer;
}- (UIBezierPath *)getLineWithStartPoint:(CGPoint)start endPoint:(CGPoint)end {UIBezierPath *line = [UIBezierPath bezierPath];[line moveToPoint:start];[line addLineToPoint:end];return line;
}- (CAShapeLayer *)getLayerWithCircle:(UIBezierPath *)circle andStrokeColor:(UIColor *)strokeColor {CAShapeLayer *circleLayer = [CAShapeLayer layer];circleLayer.path = circle.CGPath;circleLayer.strokeColor = strokeColor.CGColor;circleLayer.fillColor = nil;circleLayer.lineWidth = LINE_WIDTH;circleLayer.lineJoin = kCALineJoinBevel;return circleLayer;
}- (void)configureBezierCircle:(UIBezierPath *)circle withCenterY:(CGFloat)centerY {[circle addArcWithCenter:CGPointMake( centerY,60*SizeScale)radius:CIRCLE_RADIUSstartAngle:M_PI_2endAngle:-M_PI_2clockwise:YES];[circle addArcWithCenter:CGPointMake(centerY,60*SizeScale)radius:CIRCLE_RADIUSstartAngle:-M_PI_2endAngle:M_PI_2clockwise:YES];
}- (void)startAnimatingWithCurrentIndex:(NSInteger)index
{for (CAShapeLayer *layer in layers) {layer.hidden = YES;}[self startAnimatingLayers:circleLayers forStatus:index];
}- (void)startAnimatingLayers:(NSArray *)layersToAnimate forStatus:(NSInteger)currentStatus {float circleTimeOffset = 1;circleCounter = 0;int i = 1;//add with animationfor (CAShapeLayer *cilrclLayer in layersToAnimate) {[self.layer addSublayer:cilrclLayer];CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];animation.duration = 0.2;animation.beginTime = [cilrclLayer convertTime:CACurrentMediaTime() fromLayer:nil] + circleTimeOffset;animation.fromValue = [NSNumber numberWithFloat:0.0f];animation.toValue   = [NSNumber numberWithFloat:1.0f];animation.fillMode = kCAFillModeForwards;animation.delegate =(id <CAAnimationDelegate>) self;circleTimeOffset += .4;[cilrclLayer setHidden:YES];[cilrclLayer addAnimation:animation forKey:@"strokeCircleAnimation"];if (self.lastBlink && i == currentStatus && i != [layersToAnimate count]) {CABasicAnimation *strokeAnim = [CABasicAnimation animationWithKeyPath:@"strokeColor"];strokeAnim.fromValue         = (id) [UIColor orangeColor].CGColor;strokeAnim.toValue           = (id) [UIColor clearColor].CGColor;strokeAnim.duration          = 1.0;strokeAnim.repeatCount       = HUGE_VAL;strokeAnim.autoreverses      = NO;[cilrclLayer addAnimation:strokeAnim forKey:@"animateStrokeColor"];}i++;}
}- (void)animationDidStart:(CAAnimation *)anim {if (circleCounter < circleLayers.count) {if (anim == [circleLayers[circleCounter] animationForKey:@"strokeCircleAnimation"]) {[circleLayers[circleCounter] setHidden:NO];circleCounter++;}}
}- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {if (layerCounter >= layers.count) {return;}CAShapeLayer *lineLayer = layers[layerCounter];CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];animation.duration = 0.200;animation.fromValue = [NSNumber numberWithFloat:0.0f];animation.toValue   = [NSNumber numberWithFloat:1.0f];animation.fillMode = kCAFillModeForwards;lineLayer.hidden = NO;[self.layer addSublayer:lineLayer];[lineLayer addAnimation:animation forKey:@"strokeEndAnimation"];layerCounter++;
}@end

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demo