如何在核心图中的[plot reloadData]和注释之间进行同步？

Question

我的要求是，在拖动垂直线时 - 它应该与＆lt; ＆GT;箭头按钮。右端的视图变为绿色透明。 我的问题是，有时当我拖动垂直线时，线条，按钮是错误对齐的，如图2所示。任何人都可以帮助解决我的问题。

绘制线拖动事件的实现。enter code here

- (BOOL)plotSpace:(CPTPlotSpace *)space shouldHandlePointingDeviceDraggedEvent:(id)event atPoint:(CGPoint)point
{
CPTScatterPlot *freqRolPlot = (CPTScatterPlot *)[self.curveEditingGraphView.hostedGraph plotAtIndex:2];

        CGPoint pointInPlotArea = [self.curveEditingGraphView.hostedGraph convertPoint:point toLayer:self.curveEditingGraphView.hostedGraph.plotAreaFrame];
        NSInteger indexVal = [thePlot indexOfVisiblePointClosestToPlotAreaPoint:pointInPlotArea];
        if(pointInPlotArea.x <=24)
        {
            indexVal = 0;
            pointInPlotArea.x = 14.0f;
        }
        NSDictionary* num = [self.editableGraphData objectAtIndex:indexVal];

        if(pointInPlotArea.x <=24)
        {
            freqRollCoordinate = 20;
        }
        else{
            freqRollCoordinate = [[num objectForKey:@"x"] integerValue];
        }

        [self showDisabledView:pointInPlotArea.x];
        [self showFreqRolAnnotation:freqRollCoordinate:pointInPlotArea.x];
        [freqRolPlot reloadData];
return YES;
}



-(void)showDisabledView:(float)selectedAreaXPos
{

    CPTGraph *graph = self.curveEditingGraphView.hostedGraph;
    if (self.maskAnnotation ) {
        [graph.plotAreaFrame.plotArea removeAnnotation:self.maskAnnotation];
        self.maskAnnotation = nil;
        [nxtBtn removeFromSuperview];
        [prevBtn removeFromSuperview];
    }

    prevBtn = [UIButton buttonWithType: UIButtonTypeCustom];
    prevBtn.frame = CGRectMake(selectedAreaXPos-7,18,30,30);
    UIImage *btnImage = [UIImage imageNamed:@"PrevbtnImg"];
    [prevBtn setImage:btnImage forState:UIControlStateNormal];

    nxtBtn = [UIButton buttonWithType: UIButtonTypeCustom];
    nxtBtn.frame = CGRectMake(3,15,30,30);
    UIImage *nxtImage = [UIImage imageNamed:@"NextbtnImg"];
    [nxtBtn setImage:nxtImage forState:UIControlStateNormal];

    CGRect imageRect = CGRectMake(selectedAreaXPos,0,self.curveEditingGraphView.hostedGraph.bounds.size.width-selectedAreaXPos,self.curveEditingGraphView.hostedGraph.bounds.size.height);
    CPTBorderedLayer * imageLayer = [[CPTBorderedLayer alloc] initWithFrame:imageRect];

    CPTColor *transparentGreen = [[CPTColor greenColor] colorWithAlphaComponent:CPTFloat(0.4)];
    CPTFill* areaFill = [[CPTFill alloc] initWithColor:transparentGreen];
    imageLayer.fill = areaFill;

    [imageLayer addSublayer:nxtBtn.layer];

    self.maskAnnotation =[[CPTPlotSpaceAnnotation alloc] initWithPlotSpace:graph.defaultPlotSpace anchorPlotPoint:nil];
    self.maskAnnotation.contentLayer = imageLayer;

    [graph addSublayer:prevBtn.layer];
    [self.curveEditingGraphView.hostedGraph.plotAreaFrame.plotArea addAnnotation:self.maskAnnotation];
}