如何使用不同颜色的ios中的uibezierpath创建堆积条形图

请帮我创建一个仅使用一个贝塞尔曲线路径的堆积条形图.我正在使用下面的代码创建栏

//creating graph path
UIBezierPath *graph = [[UIBezierPath alloc]init];
[graph setLineWidth:_barWidth - _barWidth*0.1];

//Creating graph layout
self.graphLayout = [CAShapeLayer layer];
self.graphLayout.fillColor = [[UIColor clearColor] CGColor];
self.graphLayout.strokeColor = [[UIColor grayColor] CGColor];
self.graphLayout.lineWidth = _barWidth - _barWidth*0.1;;
self.graphLayout.path = [graph CGPath];
_graphLayout.lineCap = @"round";
_graphLayout.lineJoin = @"round";

[self.layer addSublayer:self.graphLayout];


for (DataSource *dataSource in self.graphCoordinateArray)
{
    [graph moveToPoint:CGPointMake((dataSource.postion*_barWidth) + _barWidth/2, STARTING_Y)];
    [graph addLineToPoint: CGPointMake((dataSource.postion*_barWidth) + _barWidth/2, dataSource.y)];
}