加载 Logo 动画 试玩

传送门：https://github.com/azheng51714/LogoLoadingView

无意间从 Dribbble 上看到一个logo 设计图，感觉非常有意思，所以决定拿来玩玩；
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分析其构造，基本确定有2部分组成，分别是：外环圆以及内部的三个收尾相连贝塞尔曲线；
设计：以外切圆心为中心点，构造一个等边三角形，计算三个顶点，pointA,pointB 以及 pointC，然后以三个顶点绘制三条贝塞尔曲线；

@interface LoadingView(){    CGFloat _turnR;//旋转半径    CGPoint _pointA;    CGPoint _pointB;    CGPoint _pointC;}@property (nonatomic,strong)     CAShapeLayer *bgLayer;@property (nonatomic,strong)     CAShapeLayer *circleLayer;@property (nonatomic,strong)     CAShapeLayer *leftLayer;@property (nonatomic,strong)     CAShapeLayer *rightLayer;@property (nonatomic,strong)     CAShapeLayer *bottomLayer;@property (nonatomic,strong)     CABasicAnimation *animation;@property (nonatomic,strong)     CABasicAnimation *turnAnimation;-(void)setUp{    _turnR = 30.0f;    _pointA = CGPointMake(self.centerX-_turnR*cos(M_PI_2/3.0), self.centerY+_turnR*sin(M_PI_2/3.0));//A点    _pointB = CGPointMake(self.centerX, self.centerY-_turnR);//B点    _pointC = CGPointMake(self.centerX+_turnR*cos(M_PI_2/3.0), self.centerY+_turnR*sin(M_PI_2/3.0));//C点    [self.layer addSublayer:self.bgLayer];    [self.bgLayer addSublayer:self.circleLayer];    [self.bgLayer addSublayer:self.leftLayer];    [self.bgLayer addSublayer:self.rightLayer];    [self.bgLayer addSublayer:self.bottomLayer];    [self.bgLayer addAnimation:self.turnAnimation forKey:nil];}-(CAShapeLayer *)bgLayer{    if (!_bgLayer) {        _bgLayer = [CAShapeLayer layer];        _bgLayer.frame = self.frame;        _bgLayer.backgroundColor = [UIColor clearColor].CGColor;    }    return _bgLayer;}-(CAShapeLayer *)circleLayer{    if (!_circleLayer) {        UIBezierPath *circlePath = [UIBezierPath bezierPathWithArcCenter:self.center radius:80.0f startAngle:0 endAngle:M_PI*2 clockwise:YES];        [circlePath closePath];        _circleLayer = [CAShapeLayer layer];        _circleLayer.path = circlePath.CGPath;        _circleLayer.backgroundColor = [UIColor clearColor].CGColor;        _circleLayer.fillColor       = [UIColor clearColor].CGColor;        _circleLayer.strokeColor = [UIColor whiteColor].CGColor;        _circleLayer.lineWidth   = 5.0f;        _circleLayer.lineCap = kCALineCapRound;        _circleLayer.lineJoin = kCALineJoinRound;        [_circleLayer addAnimation:self.animation forKey:nil];    }    return _circleLayer;}-(CABasicAnimation *)animation{    if (!_animation) {        _animation  = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];        _animation.fromValue = @0.0;        _animation.toValue = @1.0;        _animation.autoreverses = NO;//default        _animation.duration = 1.5;    }    return _animation;}-(CABasicAnimation *)turnAnimation{//开始旋转    if (!_turnAnimation) {        _turnAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];        _turnAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0 ];        _turnAnimation.duration = 1.5;        _turnAnimation.cumulative = YES;       // _turnAnimation.delegate = self;        _turnAnimation.repeatCount = MAXFLOAT;    }    return _turnAnimation;}-(CAShapeLayer *)leftLayer{    if (!_leftLayer) {        CGPoint controlPoint = CGPointMake(self.centerX - _turnR/cos(M_PI_2/3.0), self.centerY-_turnR*sin(M_PI_2/3.0)) ;        UIBezierPath *leftPath = [UIBezierPath bezierPath];        [leftPath moveToPoint:CGPointMake(_pointA.x-5.0, _pointA.y+25.0)];        [leftPath addQuadCurveToPoint:_pointB controlPoint:controlPoint];        _leftLayer = [CAShapeLayer layer];        _leftLayer.path = leftPath.CGPath;        _leftLayer.backgroundColor = [UIColor clearColor].CGColor;        _leftLayer.fillColor       = [UIColor clearColor].CGColor;        _leftLayer.strokeColor = [UIColor whiteColor].CGColor;        _leftLayer.lineWidth   = 20.0f;        [_leftLayer addAnimation:self.animation forKey:nil];    }    return _leftLayer;}-(CAShapeLayer *)rightLayer{    if (!_rightLayer) {        CGPoint controlPoint = CGPointMake(self.centerX, self.centerY+_turnR) ;        UIBezierPath *rightPath = [UIBezierPath bezierPath];        [rightPath moveToPoint:CGPointMake(_pointC.x+25.0, _pointC.y-5.0)];        [rightPath addQuadCurveToPoint:_pointA controlPoint:controlPoint];        _rightLayer = [CAShapeLayer layer];        _rightLayer.path = rightPath.CGPath;        _rightLayer.backgroundColor = [UIColor clearColor].CGColor;        _rightLayer.fillColor       = [UIColor clearColor].CGColor;        _rightLayer.strokeColor = [UIColor whiteColor].CGColor;        _rightLayer.lineWidth   = 20.0f;        [_rightLayer addAnimation:self.animation forKey:nil];    }    return _rightLayer;}-(CAShapeLayer *)bottomLayer{    if (!_bottomLayer) {        CGPoint controlPoint = CGPointMake(self.centerX + _turnR/cos(M_PI_2/3.0), self.centerY-_turnR*sin(M_PI_2/3.0)) ;        UIBezierPath *bottomPath = [UIBezierPath bezierPath];        [bottomPath moveToPoint:CGPointMake(_pointB.x-20.0, _pointB.y-20.0)];        [bottomPath addQuadCurveToPoint:_pointC controlPoint:controlPoint];        _bottomLayer = [CAShapeLayer layer];        _bottomLayer.path = bottomPath.CGPath;        _bottomLayer.backgroundColor = [UIColor clearColor].CGColor;        _bottomLayer.fillColor       = [UIColor clearColor].CGColor;        _bottomLayer.strokeColor = [UIColor whiteColor].CGColor;        _bottomLayer.lineWidth   = 20.0f;        [_bottomLayer addAnimation:self.animation forKey:nil];    }    return _bottomLayer;}