- (void)drawRect:(CGRect)rect { 
 // 间距
 CGFloat padding = 4.0;
 // 半径(小圆半径)
 CGFloat curveRadius = (rect.size.width - 2 * padding)/4.0;
 // 贝塞尔曲线
 UIBezierPath *heartPath = [UIBezierPath bezierPath];
 // 起点(圆的第一个点)
 CGPoint tipLocation = CGPointMake(rect.size.width/2, rect.size.height-padding);
 // 从起点开始画
 [heartPath moveToPoint:tipLocation];
 // (左圆的第二个点)
 CGPoint topLeftCurveStart = CGPointMake(padding, rect.size.height/2.4);
 // 添加二次曲线
 [heartPath addQuadCurveToPoint:topLeftCurveStart controlPoint:CGPointMake(topLeftCurveStart.x, topLeftCurveStart.y + curveRadius)];
 // 画圆
 [heartPath addArcWithCenter:CGPointMake(topLeftCurveStart.x+curveRadius, topLeftCurveStart.y) radius:curveRadius startAngle:M_PI endAngle:0 clockwise:YES];
 // (左圆的第二个点)
 CGPoint topRightCurveStart = CGPointMake(topLeftCurveStart.x + 2*curveRadius, topLeftCurveStart.y);
 // 画圆
 [heartPath addArcWithCenter:CGPointMake(topRightCurveStart.x+curveRadius, topRightCurveStart.y) radius:curveRadius startAngle:M_PI endAngle:0 clockwise:YES];
 // 右上角控制点
 CGPoint topRightCurveEnd = CGPointMake(topLeftCurveStart.x + 4*curveRadius, topRightCurveStart.y);
 // 添加二次曲线
 [heartPath addQuadCurveToPoint:tipLocation controlPoint:CGPointMake(topRightCurveEnd.x, topRightCurveEnd.y+curveRadius)];
 // 设置填充色
 [[UIColor redColor] setFill];
 // 填充
 [heartPath fill];
 // 设置边线
 heartPath.lineWidth = 2;
 heartPath.lineCapStyle = kCGLineCapRound;
 heartPath.lineJoinStyle = kCGLineJoinRound;
 // 设置描边色
 [[UIColor yellowColor] setStroke];
 [heartPath stroke];

}

 XMHeartView *heartView = [[XMHeartView alloc] init];
 heartView.frame = CGRectMake(100, 50, 200, 200);
 [self.view addSubview:heartView];

// 给心视图添加心跳动画
 float bigSize = 1.1;
 CABasicAnimation *pulseAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
 pulseAnimation.duration = 0.5;
 pulseAnimation.toValue = [NSNumber numberWithFloat:bigSize];
 pulseAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
 // 倒转动画
 pulseAnimation.autoreverses = YES;
 // 设置重复次数为无限大
 pulseAnimation.repeatCount = FLT_MAX;
 // 添加动画到layer
 [heartView.layer addAnimation:pulseAnimation forKey:@"transform.scale"];