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Hints

A hint is a small pop-up rectangle that shows information about a tapped series or point. A chart can display its hints as tooltips for all charts and as a Crosshair Cursor for a Cartesian Chart. A tooltip can display a beak which indicates its data point.

The hint sample

In this guide, the tooltip is used to show hint features.

How to: Allow end users to show hints

Assign a new Hint instance to the hint property to enable hints for a chart:

Tooltip displaying

The following code demonstrates how to enable hints:

self.chart.hint = [[DXHint alloc] init];

The code above uses the following symbols:

Symbol Description
DXChart.hint Gets or sets the Chart's interactive hint settings.
DXHint The Chart's interactive hint settings storage.
DXPieChart.hint Gets or sets the Pie Chart's interactive hint settings.
DXPieHint The Pie Chart's interactive hint settings storage.
Note

The hint type should be compatible with a chart to which you set it.

How to: Configure a series representation in a hint

You can disable an individual series' hints, specify a text pattern to format values, and arrange these values within tooltips.

Tooltip text format

The code below shows how to specify a tooltip text's pattern.

DXPieSeriesHintOptions* hintOptions = [[DXPieSeriesHintOptions alloc] init];
hintOptions.pointTextPattern = @"{L}: {V$#.##} millions of km²";
pieSeries.hintOptions = hintOptions;

The following symbols configure series and hint interaction:

Symbol Description
DXPieSeries.hintOptions Gets or sets pie series' hint options.
DXPieSeriesHintOptions The pie series' hint options storage.
DXSeries.hintOptions Gets or sets the series's hint options.
DXSeriesHintOptions The series's tooltip options storage.
DXSeriesCrosshairOptions The series's Crosshair options storage.
Note

You should use the DXSeriesHintOptions class for a Pie series and a Cartesian series within a Cartesian Chart that uses tooltips; in other cases you should use DXSeriesCrosshairOptions.

In the code above, the series placeholders (L and V) specify which series point values a tooltip should display in its text. The following label placeholders are available:

Placeholder Description
{S} Displays a series name.
{A} Displays a series point argument.
{L} Displays a pie series point label.
{V} Displays a series point value.
{VP} Displays a series point value as percentages.
{W} Displays a Bubble series point weight.
{O} Displays a financial series point open value.
{H} Displays a financial series point high value.
{L} Displays a financial series point low value.
{C} Displays a financial series point close value.
Note

These values can be formatted using default format strings after the $ sign. For example, in the {VP$#.##} string, VP is a placeholder, $ is a format string separator, and #.## is a format string.

How to: Programmatically interact with a hint

The chart provides methods that show or hide the hint programmatically. The chart delegate allows you to track when a chart shows or hides the hint. For example, the following code shows a hint programmatically and notifies event listeners when end users invoke hints:

@class LandAreaChartController;
@protocol LandAreaChartControllerDelegate
-(void) controller: (LandAreaChartController *)controller selectionDidChange: (LandAreaItem *)selectedItem;
@end

@interface LandAreaChartController : UIViewController<DXChartDelegate>
readwrite, nonatomic, weak, nullable id<LandAreaChartControllerDelegate> delegate;
@property IBOutlet DXPieChart *pieChart;
readwrite NSArray<LandAreaItem *> *landAreas;

-(void) showHintForItem: (LandAreaItem *)item;
@end



@implementation LandAreaChartController
- (void) viewDidLoad {
    self.pieChart.delegate = self;
}

- (void)chart:(DXChartBase *)chart didShowHint:(DXHintInfo *)info {
    if (self.delegate != nil) {
        NSNumber *itemIndex = [[info.seriesPointInfos objectAtIndex:0].dataPointIndices objectAtIndex:0];
        LandAreaItem *item = [self.landAreas objectAtIndex:itemIndex.unsignedIntegerValue];
        [self.delegate controller: self selectionDidChange:item];
    }
}

- (void)chartDidHideHint:(DXChartBase *)chart {
    [self.delegate controller: self selectionDidChange:nil];
}

- (void) showHintForItem:(LandAreaItem *)item {
    NSUInteger itemIndex = [self.landAreas indexOfObject:item];
    if (itemIndex != NSNotFound) {
        [self.pieChart showHintForPointWithIndex:itemIndex ofSeriesWithIndex:0];
    } else {
        [self.pieChart hideHint];
    }
}
@end

The table below contains members the chart tooltip API includes.

Member

Description

DXChartBase::showHint:

Shows an interactive hint (Tooltip or Crosshair Cursor) at the specified point on a chart.

DXChartBase::showHintForPointWithIndex:ofSeriesWithIndex:

Shows a hint for the specified data point.

DXChartBase::hideHint

Hides the displayed hint.

DXChartDelegate:💹didShowHint:

The action that should be done on hint showing.

DXChartDelegate::chartDidHideHint:

The action that should be done on hint hiding.

How to: Customize a tooltip's appearance

You can customize a chart's tooltip appearance using the following highlighted parameters:

Style parameters

The following code demonstrates how to configure the tooltip's appearance:

// All sizes are in screen points.
DXPieHint *hint = [[DXPieHint alloc] init];
DXHintStyle *hintStyle = [[DXHintStyle alloc] init];
DXTextStyle *hintTextStyle = [[DXTextStyle alloc] init];

self.pieChart.hint = hint;
hint.style = hintStyle;
hintStyle.textStyle = hintTextStyle;

hintStyle.backgroundColor = [UIColor colorWithWhite:0.8f alpha: 0.8f];
hintStyle.padding = UIEdgeInsetsMake(12.0f, 24.0f, 12.0f, 24.0f);
hintStyle.markerSize = 24;
hintStyle.textIndent = 12;

hintTextStyle.foregroundColor = UIColor.blackColor;
hintTextStyle.fontSize = 24;

The symbols below specify the tooltip's appearance.

Symbols Description
DXHint.style Gets or sets the Cartesian Chart's hint appearance settings.
DXHintStyle The Cartesian Chart hint's appearance settings storage.
DXPieHint.style Gets or sets a Pie Chart's hint appearance settings.
DXPieHintStyle The Pie Chart hint's appearance settings storage.