看到一个大神写的代码，引用过来让大家看看！
// 1、CAShapeLayer是一种特殊的层，可以在上面渲染图形。
// 2、CAShapeLayer继承自CALayer，可使用CALayer的所有属性。
// 3、CAShapeLayer需要和贝塞尔曲线配合使用才有意义，贝塞尔曲线为其提供渲染的图形。
// 4、使用CAShapeLayer与贝塞尔曲线可以实现不再view的drawRect方法中画出一些想要的图形。
// 关于CAShapeLayer和drawRect的比较：
// 在drawRect中绘制图形调用CoreGraphics框架中得方法，占用CPU，消耗性能大；
// CAShapeLayer属于CoreAnimation框架，通过GPU来渲染图形，节省性能。动画渲染直接提交给GPU，不消耗内存。
// 1、CAGradientLayer是一种特殊的层，用于渲染渐变效果。
// 2、CAGradientLayer继承自CALayer，可使用CALayer所有的属性。
// 3、CAGradientLayer是除了在图形上下文绘制渐变效果外的另一种方法，它不需要借助图形上下文，是直接渲染在层上的，因此易于使用。
#import "ViewController.h" #define k_SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height #define k_LAND_BEGIN_HEIGHT k_SCREEN_HEIGHT - 20 #define k_SIZE self.view.frame.size @interface ViewController () @property(strong,nonatomic)CALayer * landLayer; @property(strong,nonatomic)CAShapeLayer * greenTrack; @property(strong,nonatomic)CAShapeLayer * yellowTrack; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [UIColor lightGrayColor]; // 初始化背景渐变的天空 [self initBackgroundSky]; // 初始化雪山 [self initSnowberg]; // 加载草坪 [self initLawn]; // 加载大地 [self initLand]; // 加载黄色轨道 [self initYellowTrack]; // 加载绿色轨道 [self initGreenTrack]; // 点缀小树 [self initTree]; // 启动云彩 [self initCloudAnimation]; // 添加黄色轨道小车动画 CACurrentMediaTime系统内建时间 [self carAnimationWith:@"car" TrackLayer:_yellowTrack AnimationDuration:8.0 BeginTime:CACurrentMediaTime()]; // 添加绿色轨道小车动画 [self carAnimationWith:@"otherCar" TrackLayer:_greenTrack AnimationDuration:5.0 BeginTime:CACurrentMediaTime()]; } // 初始化背景天空渐变色 - (void)initBackgroundSky{ CAGradientLayer * backgroundLayer = [[CAGradientLayer alloc] init]; // 设置背景渐变色层的大小。要减去屏幕最下方土地那条水平线的高度 backgroundLayer.frame = CGRectMake(0, 0, k_SIZE.width, k_LAND_BEGIN_HEIGHT); UIColor * lightColor = [UIColor colorWithRed:40.0 / 255.0 green:150.0 / 255.0 blue:200.0 / 255.0 alpha:1.0]; UIColor * darkColor = [UIColor colorWithRed:255.0 / 255.0 green:250.0 / 255.0 blue:250.0 / 255.0 alpha:1.0]; backgroundLayer.colors = @[(__bridge id)lightColor.CGColor,(__bridge id)darkColor.CGColor]; // 让变色层成45度角变色 backgroundLayer.startPoint = CGPointMake(0, 0); backgroundLayer.endPoint = CGPointMake(1, 1); [self.view.layer addSublayer:backgroundLayer]; } //初始化雪山，有两个雪山 - (void)initSnowberg { // 左边第一座山顶,其实就是一个白色的三角形 CAShapeLayer * leftSnowberg = [[CAShapeLayer alloc] init]; UIBezierPath * leftSnowbergPath = [[UIBezierPath alloc] init]; // 把bezierpath的起点移动到雪山左下角 [leftSnowbergPath moveToPoint:CGPointMake(0, k_SIZE.height - 120)]; // 画一条线到山顶 [leftSnowbergPath addLineToPoint:CGPointMake(100, 100)]; // 画一条线到右下角->左下角->闭合 [leftSnowbergPath addLineToPoint:CGPointMake(k_SIZE.width / 2, k_LAND_BEGIN_HEIGHT)]; [leftSnowbergPath addLineToPoint:CGPointMake(0, k_LAND_BEGIN_HEIGHT)]; [leftSnowbergPath closePath]; leftSnowberg.path = leftSnowbergPath.CGPath; leftSnowberg.fillColor = [UIColor whiteColor].CGColor; [self.view.layer addSublayer:leftSnowberg]; // 开始画山体没有被雪覆盖的部分 CAShapeLayer * leftSnowbergBody = [[CAShapeLayer alloc] init]; UIBezierPath * leftSnowbergBodyPath = [[UIBezierPath alloc] init]; // 把bezierpath的起点移动到雪山左下角相同的位置 CGPoint startPoint = CGPointMake(0, k_SIZE.height - 120); CGPoint endPoint = CGPointMake(100, 100); CGPoint firstPathPoint = [self calculateWithXValue:20 startPoint:startPoint endpoint:endPoint]; [leftSnowbergBodyPath moveToPoint:startPoint]; [leftSnowbergBodyPath addLineToPoint:firstPathPoint]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(60, firstPathPoint.y)]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(100, firstPathPoint.y + 30)]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(140, firstPathPoint.y)]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(180, firstPathPoint.y - 20)]; CGPoint secondPathPoint = [self calculateWithXValue:(k_SIZE.width / 2 - 125) startPoint:endPoint endpoint:CGPointMake(k_SIZE.width / 2, k_LAND_BEGIN_HEIGHT)]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(secondPathPoint.x - 30, firstPathPoint.y)]; [leftSnowbergBodyPath addLineToPoint:secondPathPoint]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(k_SIZE.width / 2, k_LAND_BEGIN_HEIGHT)]; [leftSnowbergBodyPath addLineToPoint:CGPointMake(0, k_LAND_BEGIN_HEIGHT)]; [leftSnowbergBodyPath closePath]; leftSnowbergBody.path = leftSnowbergBodyPath.CGPath; UIColor * snowColor = [UIColor colorWithDisplayP3Red:139.0 /255.0 green:92.0 /255.0 blue:0.0 /255.0 alpha:1.0]; leftSnowbergBody.fillColor = snowColor.CGColor; [self.view.layer addSublayer:leftSnowbergBody]; // 中间的山 CAShapeLayer * middleSnowberg = [[CAShapeLayer alloc] init]; UIBezierPath * middleSnowbergPath = [[UIBezierPath alloc] init]; // 把bezierpath的起点移动到雪山左下角。然后画一条线到山顶，再画一条线到右下角，闭合。 CGPoint middleStartPoint = CGPointMake(k_SIZE.width / 3, k_LAND_BEGIN_HEIGHT); CGPoint middleTopPoint = CGPointMake(k_SIZE.width /2, 200); CGPoint middleEndPoint = CGPointMake(k_SIZE.width / 1.2, k_LAND_BEGIN_HEIGHT); [middleSnowbergPath moveToPoint:middleStartPoint]; [middleSnowbergPath addLineToPoint:middleTopPoint]; [middleSnowbergPath addLineToPoint:middleEndPoint]; [middleSnowbergPath closePath]; middleSnowberg.path = middleSnowbergPath.CGPath; middleSnowberg.fillColor = [UIColor whiteColor].CGColor; [self.view.layer insertSublayer:middleSnowberg above:leftSnowbergBody]; // 开始画山体没有被雪覆盖的部分 CAShapeLayer * middleSnowbergBody = [[CAShapeLayer alloc] init]; UIBezierPath * middleSnowbergBodyPath = [[UIBezierPath alloc] init]; // 把bezierpath的起点移动到雪山左下角相同的位置 [middleSnowbergBodyPath moveToPoint:middleStartPoint]; CGPoint middleFirstPathPoint = [self calculateWithXValue:(middleStartPoint.x + 70) startPoint:middleStartPoint endpoint:middleTopPoint]; [middleSnowbergBodyPath addLineToPoint:middleFirstPathPoint]; [middleSnowbergBodyPath addLineToPoint:CGPointMake(middleFirstPathPoint.x + 20, middleFirstPathPoint.y)]; [middleSnowbergBodyPath addLineToPoint:CGPointMake(middleFirstPathPoint.x + 50, middleFirstPathPoint.y + 30)]; [middleSnowbergBodyPath addLineToPoint:CGPointMake(middleFirstPathPoint.x + 80, middleFirstPathPoint.y - 10)]; [middleSnowbergBodyPath addLineToPoint:CGPointMake(middleFirstPathPoint.x + 120, middleFirstPathPoint.y + 20)]; CGPoint middleSecondPathPoint = [self calculateWithXValue:(middleEndPoint.x - 120) startPoint:middleTopPoint endpoint:middleEndPoint]; [middleSnowbergBodyPath addLineToPoint:CGPointMake(middleSecondPathPoint.x - 30, middleSecondPathPoint.y)]; [middleSnowbergBodyPath addLineToPoint:middleSecondPathPoint]; [middleSnowbergBodyPath addLineToPoint:middleEndPoint]; [middleSnowbergBodyPath closePath]; middleSnowbergBody.path = middleSnowbergBodyPath.CGPath; UIColor * middleSnowColor = [UIColor colorWithDisplayP3Red:125.0 /255.0 green:87.0 /255.0 blue:7.0 /255.0 alpha:1.0]; middleSnowbergBody.fillColor = middleSnowColor.CGColor; [self.view.layer insertSublayer:middleSnowbergBody above:middleSnowberg]; } //根据起始点，算出指定的x在这条线段上对应的y。返回这个point。知道两点，根据两点坐标，求出两点连线的斜率。y=kx+b求出点坐标。 - (CGPoint)calculateWithXValue:(CGFloat)xvalue startPoint:(CGPoint)startPoint endpoint:(CGPoint)endpoint{ // 求出两点连线的斜率 CGFloat k = (endpoint.y - startPoint.y) / (endpoint.x - startPoint.x); CGFloat b = startPoint.y - startPoint.x * k; CGFloat yvalue = k * xvalue + b; return CGPointMake(xvalue, yvalue); } //初始化草坪 - (void)initLawn { CAShapeLayer * leftLawn = [[CAShapeLayer alloc] init]; UIBezierPath * leftLawnPath = [[UIBezierPath alloc] init]; CGPoint leftStartPoint = CGPointMake(0, k_LAND_BEGIN_HEIGHT); [leftLawnPath moveToPoint:leftStartPoint]; [leftLawnPath addLineToPoint:CGPointMake(0, k_SIZE.height - 100)]; // 画一个二次贝塞尔曲线 [leftLawnPath addQuadCurveToPoint:CGPointMake(k_SIZE.width / 3.0, k_LAND_BEGIN_HEIGHT) controlPoint:CGPointMake(k_SIZE.width / 5.0, k_SIZE.height - 100)]; leftLawn.path = leftLawnPath.CGPath; leftLawn.fillColor = [UIColor colorWithDisplayP3Red:82.0 / 255.0 green:177.0 / 255.0 blue:52.0 / 255.0 alpha:1.0].CGColor; [self.view.layer addSublayer:leftLawn]; CAShapeLayer * rightLawn = [[CAShapeLayer alloc] init]; UIBezierPath * rightLawnPath = [[UIBezierPath alloc] init]; [rightLawnPath moveToPoint:leftStartPoint]; // 画一个二次贝塞尔曲线 [rightLawnPath addQuadCurveToPoint:CGPointMake(k_SIZE.width, k_SIZE.height - 80) controlPoint:CGPointMake(k_SIZE.width / 2.0, k_SIZE.height - 100)]; [rightLawnPath addLineToPoint:CGPointMake(k_SIZE.width, k_LAND_BEGIN_HEIGHT)]; rightLawn.path = rightLawnPath.CGPath; rightLawn.fillColor = [UIColor colorWithDisplayP3Red:92.0/255.0 green:195.0/255.0 blue:52.0/255.0 alpha:1.0].CGColor; [self.view.layer insertSublayer:rightLawn above:leftLawn]; } //初始化土地 - (void)initLand { _landLayer = [[CALayer alloc] init]; _landLayer.frame = CGRectMake(0, k_LAND_BEGIN_HEIGHT, k_SIZE.width, 20); _landLayer.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"ground"]].CGColor; [self.view.layer addSublayer:_landLayer]; } //初始化黄色轨道 - (void)initYellowTrack { _yellowTrack = [[CAShapeLayer alloc] init]; _yellowTrack.lineWidth = 5; _yellowTrack.strokeColor = [UIColor colorWithDisplayP3Red:210.0 / 255.0 green:179.0 / 255.0 blue:54.0 / 255.0 alpha:1.0].CGColor; UIBezierPath * trackPath = [[UIBezierPath alloc] init]; // 画一个三次贝塞尔曲线 + 一个二次贝塞尔曲线 // 左侧两个拐弯的三次贝塞尔曲线 [trackPath moveToPoint:CGPointMake(0, k_SIZE.height - 60)]; [trackPath addCurveToPoint:CGPointMake(k_SIZE.width / 1.5, k_SIZE.height / 2.0 - 20) controlPoint1:CGPointMake(k_SIZE.width / 6.0, k_SIZE.height - 200) controlPoint2:CGPointMake(k_SIZE.width / 3.0, k_SIZE.height + 50)]; // 右侧一个弯度的二次贝塞尔曲线 [trackPath addQuadCurveToPoint:CGPointMake(k_SIZE.width + 50, k_SIZE.height / 3.0) controlPoint:CGPointMake(k_SIZE.width - 100, 50)]; [trackPath addLineToPoint:CGPointMake(k_SIZE.width + 10, k_SIZE.height + 10)]; [trackPath addLineToPoint:CGPointMake(0, k_SIZE.height + 10)]; _yellowTrack.fillColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"yellow"]].CGColor; _yellowTrack.path = trackPath.CGPath; [self.view.layer insertSublayer:_yellowTrack below:_landLayer]; // 为了能够让弧线更好看一点，需要加入镂空的虚线 CAShapeLayer * trackLine = [[CAShapeLayer alloc] init]; trackLine.lineCap = kCALineCapRound; trackLine.strokeColor = [UIColor whiteColor].CGColor; trackLine.lineDashPattern = @[@1.0,@6.0]; //宽度，间距 trackLine.lineWidth = 2.5; trackLine.fillColor = [UIColor clearColor].CGColor; trackLine.path = trackPath.CGPath; [_yellowTrack addSublayer:trackLine]; } // 初始化绿色轨道 - (void)initGreenTrack { _greenTrack = [[CAShapeLayer alloc] init]; _greenTrack.lineWidth = 5; _greenTrack.strokeColor = [UIColor colorWithDisplayP3Red:0.0 / 255.0 green:147.0 / 255.0 blue:163.0 /255.0 alpha:1.0].CGColor; // 绿色铁轨的火车从右侧进入，所以从右侧开始绘画。需要画三条曲线，右边一条 + 中间的圆圈 + 左边一条 UIBezierPath * path = [[UIBezierPath alloc] init]; [path moveToPoint:CGPointMake(k_SIZE.width + 10, k_LAND_BEGIN_HEIGHT)]; [path addLineToPoint:CGPointMake(k_SIZE.width + 10, k_SIZE.height - 70)]; [path addQuadCurveToPoint:CGPointMake(k_SIZE.width / 1.5, k_SIZE.height - 70) controlPoint:CGPointMake(k_SIZE.width - 150, 200)]; // 画圆圈 [path addArcWithCenter:CGPointMake(k_SIZE.width / 1.6, k_SIZE.height - 140) radius:70 startAngle:M_PI_2 endAngle:2.5 * M_PI clockwise:YES]; [path addCurveToPoint:CGPointMake(0, k_SIZE.height - 100) controlPoint1:CGPointMake(k_SIZE.width / 1.8 - 60, k_SIZE.height - 60) controlPoint2:CGPointMake(150, k_SIZE.height / 2.3)]; [path addLineToPoint:CGPointMake(- 10, k_LAND_BEGIN_HEIGHT)]; _greenTrack.path = path.CGPath; _greenTrack.fillColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"green"]].CGColor; [self.view.layer addSublayer:_greenTrack]; // 为了能够让弧线更好看一点，需要加入镂空的虚线 CAShapeLayer * trackLine = [[CAShapeLayer alloc] init]; trackLine.lineCap = kCALineCapRound; trackLine.strokeColor = [UIColor whiteColor].CGColor; trackLine.lineDashPattern = @[@1.0,@6.0]; trackLine.lineWidth = 2.5; trackLine.fillColor = [UIColor clearColor].CGColor; trackLine.path = path.CGPath; [_greenTrack addSublayer:trackLine]; } // 添加点缀的小树 - (void)initTree { [self addTreesWithNumber:7 treeFrame:CGRectMake(0, k_LAND_BEGIN_HEIGHT - 20, 13, 23)]; [self addTreesWithNumber:7 treeFrame:CGRectMake(0, k_LAND_BEGIN_HEIGHT - 64, 18, 32)]; [self addTreesWithNumber:5 treeFrame:CGRectMake(0, k_LAND_BEGIN_HEIGHT - 90, 13, 23)]; } // 添加小树 - (void)addTreesWithNumber:(NSInteger)treesNumber treeFrame:(CGRect)frame { UIImage * tree = [UIImage imageNamed:@"tree"]; for (NSInteger i = 0; i < treesNumber + 1; i++) { CALayer * treeLayer = [[CALayer alloc] init]; treeLayer.contents = (__bridge id _Nullable)(tree.CGImage); treeLayer.frame = CGRectMake(k_SIZE.width - 50 * i * (arc4random_uniform(4) + 1), frame.origin.y, frame.size.width, frame.size.height); [self.view.layer insertSublayer:treeLayer above:_greenTrack]; } } // 云彩的动画 - (void)initCloudAnimation { CALayer * cloud = [[CALayer alloc]init]; cloud.contents = (__bridge id _Nullable)([UIImage imageNamed:@"cloud"].CGImage); cloud.frame = CGRectMake(0, 0, 63, 20); [self.view.layer addSublayer:cloud]; UIBezierPath * cloudPath = [[UIBezierPath alloc] init]; [cloudPath moveToPoint:CGPointMake(k_SIZE.width + 63, 50)]; [cloudPath addLineToPoint:CGPointMake(- 63, 50)]; CAKeyframeAnimation * ani = [CAKeyframeAnimation animationWithKeyPath:@"position"]; ani.path = cloudPath.CGPath; ani.duration = 30; ani.autoreverses = NO; ani.repeatCount = CGFLOAT_MAX; /* kCAAnimationLinear calculationMode的默认值,表示当关键帧为座标点的时候,关键帧之间直接直线相连进行插值计算 * kCAAnimationDiscrete 离散的,就是不进行插值计算,所有关键帧直接逐个进行显示 * kCAAnimationPaced 使得动画均匀进行,而不是按keyTimes设置的或者按关键帧平分时间,此时keyTimes和timingFunctions无效 * kCAAnimationCubic 对关键帧为座标点的关键帧进行圆滑曲线相连后插值计算,对于曲线的形状还可以通过tensionValues,continuityValues,biasValues来进行调整自定义,这里的数学原理是Kochanek–Bartels spline,这里的主要目的是使得运行的轨迹变得圆滑; * kCAAnimationCubicPaced 看这个名字就知道和kCAAnimationCubic有一定联系,其实就是在kCAAnimationCubic的基础上使得动画运行变得均匀,就是系统时间内运动的距离相同,此时keyTimes以及timingFunctions也是无效的. */ ani.calculationMode = kCAAnimationPaced; [cloud addAnimation:ani forKey:@"position"]; } //抽取过山车的动画 - (CAKeyframeAnimation *)carAnimationWith:(NSString *)carImageName TrackLayer:(CAShapeLayer *)track AnimationDuration:(CFTimeInterval)duration BeginTime:(CFTimeInterval)beginTime { CALayer * car = [[CALayer alloc] init]; car.frame = CGRectMake(0, 0, 22, 15); car.contents = (__bridge id _Nullable)([UIImage imageNamed:carImageName].CGImage); CAKeyframeAnimation * ani = [CAKeyframeAnimation animationWithKeyPath:@"position"]; ani.path = track.path; ani.duration = duration; ani.beginTime = beginTime; ani.autoreverses = NO; ani.repeatCount = CGFLOAT_MAX; ani.calculationMode = kCAAnimationPaced; ani.rotationMode = kCAAnimationRotateAuto; [track addSublayer:car]; [car addAnimation:ani forKey:@"carAni"]; return ani; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } @end