核心情节：个性化情节

Question

我正在试验 iOS 的 Core Plot 库。我已经成功地显示了包含我的信息的图表，但是我无法根据需要个性化可视化。
我正在尝试使用一个简单的散点图来显示用户在两个日期之间每天行驶的距离。我已经设法创建用于绘图的数据，但我很难个性化绘图，也许使用过此库的人可以帮助我;)
我的问题是：
- 如果我只显示 x 轴和 y 轴的正方向，我将看不到标签。
- 例如，如果两个日期之间有 31 天，则 x 轴从 0 到 30。如何更改标签以显示日期，例如 startDate + x。 这是我到目前为止所做的：

@interface DistanceChart : CPGraphHostingView <CPPlotDataSource> {
    CPXYGraph *graph;
    NSMutableArray *dataForPlot;
    RouteManager *routeManager;
    NSDate *startDate;
    NSDate *endDate;
}

@property (nonatomic, retain) NSMutableArray *dataForPlot;
@property (nonatomic, retain) RouteManager *routeManager;
@property (nonatomic, retain) NSDate *startDate;
@property (nonatomic, retain) NSDate *endDate;

- (void)initPlot;

@end



@implementation DistanceChart
@synthesize dataForPlot;
@synthesize routeManager;
@synthesize startDate;
@synthesize endDate;

- (void)initPlot {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"dd-MM-yyyy"];
    self.startDate = [dateFormatter dateFromString:@"01-05-2011"];
    self.endDate = [dateFormatter dateFromString:@"31-05-2011"];

    //get the data
    self.dataForPlot = [routeManager getTotalDistanceByDay:routeManager.routes from:startDate to:endDate];
    NSLog(@"Data: %@", dataForPlot);


    graph = [[CPXYGraph alloc] initWithFrame:CGRectZero];
    self.hostedGraph = graph;

    graph.paddingLeft = 5;
    graph.paddingTop = 5;
    graph.paddingRight = 5;
    graph.paddingBottom = 5;

    // Setup plot space
    int days = [endDate timeIntervalSinceDate:startDate] / 60 / 60 / 24 + 1;

    CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace;
    plotSpace.allowsUserInteraction = YES;
    plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0) length:CPDecimalFromFloat(days)];
    plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0) length:CPDecimalFromFloat(15)]; //TODO: set maximum Y according to max distance

    // Axes
    CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet;
    CPXYAxis *x = axisSet.xAxis;
    x.majorIntervalLength = CPDecimalFromString(@"1");
    x.orthogonalCoordinateDecimal = CPDecimalFromString(@"0");
    x.minorTicksPerInterval = 1;

    CPXYAxis *y = axisSet.yAxis;
    y.majorIntervalLength = CPDecimalFromString(@"1");
    y.minorTicksPerInterval = 1;
    y.orthogonalCoordinateDecimal = CPDecimalFromString(@"0");
    x.labelRotation = M_PI/8;

    // Create a green plot area
    CPScatterPlot *dataSourceLinePlot = [[[CPScatterPlot alloc] init] autorelease];
    dataSourceLinePlot.identifier = @"Green Plot";

    CPMutableLineStyle *lineStyle = [[dataSourceLinePlot.dataLineStyle mutableCopy] autorelease];
    lineStyle.lineWidth = 2.f;
    lineStyle.lineColor = [CPColor greenColor];

    dataSourceLinePlot.dataLineStyle = lineStyle;
    dataSourceLinePlot.dataSource = self;

    // Put an area gradient under the plot above
    CPColor *areaColor = [CPColor colorWithComponentRed:0.3 green:1.0 blue:0.3 alpha:0.8];
    CPGradient *areaGradient = [CPGradient gradientWithBeginningColor:areaColor endingColor:[CPColor clearColor]];
    areaGradient.angle = -90.0f;
    CPFill *areaGradientFill = [CPFill fillWithGradient:areaGradient];
    dataSourceLinePlot.areaFill = areaGradientFill;
    dataSourceLinePlot.areaBaseValue = CPDecimalFromString(@"1.75");

    // Animate in the new plot, as an example
    dataSourceLinePlot.opacity = 0.0f;
    dataSourceLinePlot.cachePrecision = CPPlotCachePrecisionDecimal;
    [graph addPlot:dataSourceLinePlot];

    CABasicAnimation *fadeInAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
    fadeInAnimation.duration = 1.0f;
    fadeInAnimation.removedOnCompletion = NO;
    fadeInAnimation.fillMode = kCAFillModeForwards;
    fadeInAnimation.toValue = [NSNumber numberWithFloat:1.0];
    [dataSourceLinePlot addAnimation:fadeInAnimation forKey:@"animateOpacity"];
}

#pragma mark -
#pragma mark Plot Data Source Methods

- (NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot 
{
    return [dataForPlot count];
}

- (NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index 
{
    NSDecimalNumber *num = [[dataForPlot objectAtIndex:index] valueForKey:(fieldEnum == CPScatterPlotFieldX ? @"x" : @"y")];

    return num;
}

- (CPLayer *)dataLabelForPlot:(CPPlot *)plot recordIndex:(NSUInteger)index
{
    return nil;
}

- (void)dealloc {
    [dataForPlot release];
    [routeManager release];
    [startDate release];
    [endDate release];

    [super dealloc];
}

@end

Answer 1

您可能需要增加填充才能显示标签。您可能还需要在 plotAreaFrame 上添加填充。

Core Plot 中包含几个示例程序（“DatePlot”和“MinorTickLabels”），展示了如何在轴上设置日期和时间的格式。