In SciChart iOS, it is possible to check if a line segment, point, candle, column or area has been tapped by the user. To do this, we use the Hit-Test API.

Each SCIRenderableSeriesBase type has a HitTestProvider. If you call Hit-Test on the provider passing in a screen coordinate (X,Y pixel coordinate), SciChart will return a SCIHitTestInfo instance containing information about the hit-test.

// HitTestAPIChart.m

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2019. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// HitTestAPIChart.m is part of the SCICHART® Examples. Permission is hereby granted
// to modify, create derivative works, distribute and publish any part of this source
// code whether for commercial, private or personal use.
//
// The SCICHART® examples are distributed in the hope that they will be useful, but
// without any warranty. It is provided "AS IS" without warranty of any kind, either
// expressed or implied.
//******************************************************************************

#import "HitTestAPIChart.h"
#import "SCDDataManager.h"
#import "SCDAlertPresenter.h"

@implementation HitTestAPIChart {
    SCIHitTestInfo *_hitTestInfo;
    SCDAlertPresenter * _alertPresenter;
}

- (Class)associatedType { return SCIChartSurface.class; }

- (void)commonInit {
    _hitTestInfo = [SCIHitTestInfo new];
    [self.surface addGestureRecognizer:[[SCITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)]];
}

- (void)initExample {
    id<ISCIAxis> xAxis = [SCINumericAxis new];
    id<ISCIAxis> yAxis = [SCINumericAxis new];
    yAxis.axisAlignment = SCIAxisAlignment_Left;
    yAxis.growBy = [[SCIDoubleRange alloc] initWithMin:0 max:0.1];
    
    double xData[] = {0, 1,   2,   3,   4,   5,    6,   7,    8,   9};
    double yData[] = {0, 0.1, 0.3, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.1};
    SCIDoubleValues *xValues = [[SCIDoubleValues alloc] initWithItems:xData count:10];
    SCIDoubleValues *yValues = [[SCIDoubleValues alloc] initWithItems:yData count:10];
    
    SCIXyDataSeries *dataSeries0 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    dataSeries0.seriesName = @"Line Series";
    [dataSeries0 appendValuesX:xValues y:yValues];
    
    SCIXyDataSeries *dataSeries1 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    dataSeries1.seriesName = @"Mountain Series";
    [dataSeries1 appendValuesX:xValues y:[SCDDataManager scaleValues:yValues scale:0.7]];
    
    SCIXyDataSeries *dataSeries2 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    dataSeries2.seriesName = @"Column Series";
    [dataSeries2 appendValuesX:xValues y:[SCDDataManager scaleValues:yValues scale:0.5]];

    SCIOhlcDataSeries *dataSeries3 = [[SCIOhlcDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    dataSeries3.seriesName = @"CandleStick Series";
    [dataSeries3 appendValuesX:xValues open:[SCDDataManager offset:yValues offset:0.5] high:[SCDDataManager offset:yValues offset:1] low:[SCDDataManager offset:yValues offset:0.3] close:[SCDDataManager offset:yValues offset:0.7]];
    
    SCIEllipsePointMarker *pointMarker = [SCIEllipsePointMarker new];
    pointMarker.size = CGSizeMake(30, 30);
    pointMarker.fillStyle = [[SCISolidBrushStyle alloc] initWithColorCode:0xFF4682B4];
    pointMarker.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFFE6E6FA thickness:2];
    
    SCIFastLineRenderableSeries *lineSeries = [SCIFastLineRenderableSeries new];
    lineSeries.dataSeries = dataSeries0;
    lineSeries.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFF4682B4 thickness:2];
    lineSeries.pointMarker = pointMarker;
    
    SCIFastMountainRenderableSeries *mountainSeries = [SCIFastMountainRenderableSeries new];
    mountainSeries.dataSeries = dataSeries1;
    mountainSeries.areaStyle = [[SCISolidBrushStyle alloc] initWithColorCode:0xFFB0C4DE];
    mountainSeries.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFF4682B4 thickness:2];
    
    SCIFastColumnRenderableSeries *columnSeries = [SCIFastColumnRenderableSeries new];
    columnSeries.dataSeries = dataSeries2;
    
    SCIFastCandlestickRenderableSeries *candlestickSeries = [SCIFastCandlestickRenderableSeries new];
    candlestickSeries.dataSeries = dataSeries3;
    
    [SCIUpdateSuspender usingWithSuspendable:self.surface withBlock:^{
        [self.surface.xAxes add:xAxis];
        [self.surface.yAxes add:yAxis];
        [self.surface.renderableSeries add:lineSeries];
        [self.surface.renderableSeries add:mountainSeries];
        [self.surface.renderableSeries add:columnSeries];
        [self.surface.renderableSeries add:candlestickSeries];

        [SCIAnimations scaleSeries:lineSeries duration:1.5 andEasingFunction:[SCICubicEase new]];
        [SCIAnimations scaleSeries:mountainSeries duration:1.5 andEasingFunction:[SCICubicEase new]];
        [SCIAnimations scaleSeries:columnSeries duration:1.5 andEasingFunction:[SCICubicEase new]];
        [SCIAnimations scaleSeries:candlestickSeries duration:1.5 andEasingFunction:[SCICubicEase new]];
    }];
}

- (void)handleSingleTap:(SCITapGestureRecognizer *)recognizer {
    CGPoint location = [recognizer locationInView:recognizer.view];
    
    CGPoint hitTestPoint = [self.surface translatePoint:location hitTestable:self.surface.renderableSeriesArea];

    NSMutableString *resultString = [NSMutableString stringWithFormat:@"Touch at: (%.0f, %.0f)", hitTestPoint.x, hitTestPoint.y];
    SCIRenderableSeriesCollection *seriesCollection = self.surface.renderableSeries;
    for (NSInteger i = 0, count = seriesCollection.count; i < count; i++) {
        id<ISCIRenderableSeries> rSeries = seriesCollection[i];
        [rSeries hitTest:_hitTestInfo at:hitTestPoint];

        [resultString appendString:[NSString stringWithFormat:@"\n%@ - %@", rSeries.dataSeries.seriesName, _hitTestInfo.isHit ? @"YES" : @"NO"]];
    }

    _alertPresenter = [[SCDAlertPresenter alloc] initWithMessage:resultString];
}

@end

// HitTestAPIChart.swift

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2019. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// HitTestAPIChart.swift is part of the SCICHART® Examples. Permission is hereby granted
// to modify, create derivative works, distribute and publish any part of this source
// code whether for commercial, private or personal use.
//
// The SCICHART® examples are distributed in the hope that they will be useful, but
// without any warranty. It is provided "AS IS" without warranty of any kind, either
// expressed or implied.
//******************************************************************************

class HitTestAPIChart: SCDSingleChartViewController<SCIChartSurface> {
    
    override var associatedType: AnyClass { return SCIChartSurface.self }
    
    private let hitTestInfo = SCIHitTestInfo()
    private var alertPresenter: SCDAlertPresenter!
  
    override func commonInit() {
        surface.addGestureRecognizer(SCITapGestureRecognizer(target: self, action: #selector(handleSingleTap)))
    }
    
    override func initExample() {
        let xAxis = SCINumericAxis()
        let yAxis = SCINumericAxis()
        yAxis.axisAlignment = .left
        yAxis.growBy = SCIDoubleRange(min: 0, max: 0.1)
       
        let xData: [Double] = [0, 1,   2,   3,   4,   5,    6,   7,    8,   9]
        let yData: [Double] = [0, 0.1, 0.3, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.1]
        let xValues = SCIDoubleValues()
        let yValues = SCIDoubleValues()
        for i in 0 ..< xData.count {
            xValues.add(xData[i])
            yValues.add(yData[i])
        }
        
        let dataSeries0 = SCIXyDataSeries(xType: .double, yType: .double)
        dataSeries0.seriesName = "Line Series"
        dataSeries0.append(x: xValues, y: yValues)
        
        let dataSeries1 = SCIXyDataSeries(xType: .double, yType: .double)
        dataSeries1.seriesName = "Mountain Series"
        dataSeries1.append(x: xValues, y: SCDDataManager .scale(yValues, scale: 0.7))
        
        let dataSeries2 = SCIXyDataSeries(xType: .double, yType: .double)
        dataSeries2.seriesName = "Column Series"
        dataSeries2.append(x: xValues, y: SCDDataManager .scale(yValues, scale: 0.5))

        let dataSeries3 = SCIOhlcDataSeries(xType: .double, yType: .double)
        dataSeries3.seriesName = "Candlestick Series"
        dataSeries3.append(x: xValues, open: SCDDataManager.offset(yValues, offset: 0.5), high: SCDDataManager.offset(yValues, offset: 1), low: SCDDataManager.offset(yValues, offset: 0.3), close: SCDDataManager.offset(yValues, offset: 0.7))

        let pointMarker = SCIEllipsePointMarker()
        pointMarker.size = CGSize(width: 30, height: 30)
        pointMarker.fillStyle = SCISolidBrushStyle(color: 0xFF4682B4)
        pointMarker.strokeStyle = SCISolidPenStyle(color: 0xFFE6E6FA, thickness: 2)

        let lineSeries = SCIFastLineRenderableSeries()
        lineSeries.dataSeries = dataSeries0
        lineSeries.strokeStyle = SCISolidPenStyle(color: 0xFF4682B4, thickness: 2)
        lineSeries.pointMarker = pointMarker
        
        let mountainSeries = SCIFastMountainRenderableSeries()
        mountainSeries.dataSeries = dataSeries1
        mountainSeries.areaStyle = SCISolidBrushStyle(color: 0xFFB0C4DE)
        mountainSeries.strokeStyle = SCISolidPenStyle(color: 0xFF4682B4, thickness: 2)

        let columnSeries = SCIFastColumnRenderableSeries()
        columnSeries.dataSeries = dataSeries2

        let candlestickSeries = SCIFastCandlestickRenderableSeries()
        candlestickSeries.dataSeries = dataSeries3;
        
        SCIUpdateSuspender.usingWith(surface) {
            self.surface.xAxes.add(xAxis)
            self.surface.yAxes.add(yAxis)
            self.surface.renderableSeries.add(items: lineSeries, mountainSeries, columnSeries, candlestickSeries)
            
            SCIAnimations.scale(lineSeries, duration: 1.5, andEasingFunction: SCICubicEase())
            SCIAnimations.scale(mountainSeries, duration: 1.5, andEasingFunction: SCICubicEase())
            SCIAnimations.scale(columnSeries, duration: 1.5, andEasingFunction: SCICubicEase())
            SCIAnimations.scale(candlestickSeries, duration: 1.5, andEasingFunction: SCICubicEase())
        }
    }
    
    @objc fileprivate func handleSingleTap(_ recognizer: SCITapGestureRecognizer) {
        let location = recognizer.location(in: recognizer.view!)
        let hitTestPoint = surface.translate(location, hitTestable: surface.renderableSeriesArea)

        var resultString = String(format: "Touch at: (%.0f, %.0f)", hitTestPoint.x, hitTestPoint.y)
        let seriesCollection = surface.renderableSeries
        for i in 0 ..< seriesCollection.count {
            let rSeries = seriesCollection[i]
            rSeries.hitTest(hitTestInfo, at: hitTestPoint)

            resultString.append("\n\(rSeries.dataSeries!.seriesName!) - \(hitTestInfo.isHit ? "true" : "false")")
        }

        alertPresenter = SCDAlertPresenter(message: resultString)
    }
}

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