Ios 是否可以将UIImage添加到CPTGraph？

我正在尝试使用Core Plot将图像添加到图形中，我希望图像在拖动或挤压时随图形移动。我尝试了下面的代码，但没有成功。谁能告诉我怎么做

CALayer *subLayer = [CALayer layer];
subLayer.contents = [UIImage imageNamed:@"image.png"];
subLayer.position = CGPointMake(100, 120);
[_graph addSublayer:subLayer];

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使用打印空间注释：

CPTBorderedLayer *imageLayer = [[CPTBorderedLayer alloc] initWithFrame:imageFrame];
imageLayer.fill = [CPTFill fillWithImage:[CPTImage imageNamed:@"image.png"]];

NSArray *plotPoint = @[xCoordinate, yCoordinate];
CPTPlotSpaceAnnotation *imageAnnotation = [[CPTPlotSpaceAnnotation alloc] initWithPlotSpace:plotSpace
                                                                            anchorPlotPoint:plotPoint];
imageAnnotation.contentLayer = imageLayer;