@interface ViewController () @property (strong, nonatomic) CADisplayLink *displayLink;@property (strong, nonatomic) CAShapeLayer *shapeLayer;@property (strong, nonatomic) UIBezierPath *path;@property (strong, nonatomic) CAShapeLayer *shapeLayer2;@property (strong, nonatomic) UIBezierPath *path2;@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad];  _shapeLayer = [CAShapeLayer layer]; _shapeLayer.frame = CGRectMake(0, 100, 375, 150); [self.view.layer addSublayer:_shapeLayer];  _shapeLayer2 = [CAShapeLayer layer]; _shapeLayer2.frame = CGRectMake(0, 100, 375, 150); [self.view.layer addSublayer:_shapeLayer2]; _shapeLayer.fillColor = [[UIColor yellowColor] colorWithAlphaComponent:0.3].CGColor; _shapeLayer2.fillColor = [[UIColor blueColor] colorWithAlphaComponent:0.3].CGColor;  _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(drawPath)]; [_displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes]; } - (void)drawPath { static double i = 0;  CGFloat A = 10.f;//A振幅 CGFloat k = 0;//y軸偏移 CGFloat ω = 0.03;//角速度ω變大，則波形在X軸上收縮（波形變緊密）；角速度ω變小，則波形在X軸上延展（波形變稀疏）。不等于0 CGFloat φ = 0 + i;//初相，x=0時的相位；反映在坐標系上則為圖像的左右移動。 //y=Asin(ωx+φ)+k  _path = [UIBezierPath bezierPath]; _path2 = [UIBezierPath bezierPath];  [_path moveToPoint:CGPointZero]; [_path2 moveToPoint:CGPointZero]; for (int i = 0; i < 376; i ++) {  CGFloat x = i;  CGFloat y = A * sin(ω*x+φ)+k;  CGFloat y2 = A * cos(ω*x+φ)+k;  [_path addLineToPoint:CGPointMake(x, y)];  [_path2 addLineToPoint:CGPointMake(x, y2)]; } [_path addLineToPoint:CGPointMake(375, -100)]; [_path addLineToPoint:CGPointMake(0, -100)]; _path.lineWidth = 1; _shapeLayer.path = _path.CGPath;  [_path2 addLineToPoint:CGPointMake(375, -100)]; [_path2 addLineToPoint:CGPointMake(0, -100)]; _path2.lineWidth = 1;  _shapeLayer2.path = _path2.CGPath;  i += 0.1; if (i > M_PI * 2) {  i = 0;//防止i越界 }}