iOS CAShapeLayer和UIBezierPath无限绘制图线如何不卡

Question

现在公司有一个要求：连接蓝牙BLE4.0之后，获取传递过来的数据，然后以点的形式连接成线。
我采用的是CAShapeLayer和UIBezierPath绘制曲线，当一开始点比较少的时候，可以非常流畅的把线画出来
但是当点的数目达到3000左右，就会开始卡顿。
因为我们的数据是每秒25个数据，在scrollView上显示的时候回非常卡顿，请问有什么好办法来解决这个问题呢？？？？

以下是绘制的代码：

UIBezierPath *path = [[UIBezierPath alloc] init];
path.usesEvenOddFillRule = YES;
NSString * tt=nil;
float height=self.topScrollView.frame.size.height;

if (objc.BLE_View.minusRangeValue==0) {
     tt=[NSString stringWithFormat:@"{%.2f,%.2f}",timer_number*1.2,objc.BLE_View.positive_k*height*(1-[string floatValue]/[objc.BLE_View.positiveRangeValue floatValue])];
}
else
{
    if (isPositive) {
        tt=[NSString stringWithFormat:@"{%.2f,%.2f}",timer_number*1.2,objc.BLE_View.positive_k*height*(1-[string floatValue]/[objc.BLE_View.positiveRangeValue floatValue])];


    }
    else
    {
        tt=[NSString stringWithFormat:@"{%.2f,%.2f}",timer_number*1.2,objc.BLE_View.minus_k*height*(1+[string floatValue]/[objc.BLE_View.minusRangeValue floatValue])];
    }
}



if (!pointLast.x) {
    pointLast=CGPointFromString(tt);
    [path moveToPoint:pointLast];
    [path addLineToPoint:pointLast];
}
else
{
    [path moveToPoint:pointLast];

    [path addLineToPoint:pointLast];

    [path addLineToPoint:CGPointFromString(tt)];

}


//create shape layer
CAShapeLayer *shapeLayer = [CAShapeLayer layer];

shapeLayer.drawsAsynchronously=YES;
shapeLayer.strokeColor = [UIColor greenColor].CGColor;
shapeLayer.fillColor = [UIColor whiteColor].CGColor;
shapeLayer.lineWidth = 3;
shapeLayer.lineJoin = kCALineJoinRound;//终点处理
shapeLayer.lineCap = kCALineCapRound;//线条拐角
shapeLayer.path = path.CGPath;


//add it to our view


[shapeLayerArr addObject:shapeLayer];


dispatch_sync(dispatch_get_main_queue(), ^{

    [_topScrollView.layer addSublayer:shapeLayer];


    // 设置layer的animation
    _topScrollView.layer.shouldRasterize = YES;

    NSLog(@"------》%f,-------》%f",pointLast.x-10,pointLast.y-10);

    [_topScrollView setNeedsDisplayInRect:CGRectMake(pointLast.x-10, pointLast.y-10, 40, 40)];
    [_topScrollView.layer setNeedsDisplayInRect:CGRectMake(pointLast.x-10, pointLast.y-10, 40, 40)];

    if (pointLast.x>_topScrollView.contentSize.width) {


        _topScrollView.contentSize=CGSizeMake(_topScrollView.contentSize.width+_topScrollView.frame.size.width, 0);
        _topScrollView.contentOffset=CGPointMake(pointLast.x, 0);

    }

    pointLast=CGPointFromString(tt);
});

Answer 1

http://blog.csdn.net/volcan1987/article/details/9969455