Demonstrates the difference between FIFO and standard DataSeries. A FIFO series discards old data-points once a predefined number of points is met. This type of data-series is extremely efficient for scrolling charts, where you do not care about discarded (off-screen) data.

FIFO Series can be used in more ways than just scrolling a chart. For instance, reload the entire FIFO buffer each frame to get a Spectrum Analyzer style chart. Or, use FIFO series and set the XAxis.VisibleRange to achieve an ECG style chart.

// FIFOSpeedTestSciChart.m

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2019. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// FifoScrollingChartView.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 "FifoScrollingChartView.h"
#import "SCDToolbarItem.h"
#import "SCDDataManager.h"
#import "SCDRandomUtil.h"
#import "SCDToolbarButtonsGroup.h"

static int const FifoCapacicty = 50;
static double const TimeInterval = 30.0;
static double const OneOverTimeInterval = 1.0 / TimeInterval;
static double const VisibleRangeMax = FifoCapacicty * OneOverTimeInterval;
static double const GrowBy = VisibleRangeMax * 0.1;

@implementation FifoScrollingChartView {
    NSTimer *_timer;
    SCIXyDataSeries *_ds1;
    SCIXyDataSeries *_ds2;
    SCIXyDataSeries *_ds3;
    
    double _t;
    BOOL _isRunning;
}

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

- (NSArray<id<ISCDToolbarItem>> *)provideExampleSpecificToolbarItems {
    __weak typeof(self) wSelf = self;

    return @[[[SCDToolbarButtonsGroup alloc] initWithToolbarItems:@[
        [[SCDToolbarItem alloc] initWithTitle:@"Start" image:[SCIImage imageNamed:@"chart.play"] andAction:^{ self->_isRunning = YES; }],
        [[SCDToolbarItem alloc] initWithTitle:@"Pause" image:[SCIImage imageNamed:@"chart.pause"] andAction:^{ self->_isRunning = NO; }],
        [[SCDToolbarItem alloc] initWithTitle:@"Stop" image:[SCIImage imageNamed:@"chart.stop"] andAction:^{
            self->_isRunning = NO;
            [wSelf resetChart];
        }],
    ]]];
}

- (void)initExample {
    id<ISCIAxis> xAxis = [SCINumericAxis new];
    xAxis.autoRange = SCIAutoRange_Never;
    xAxis.visibleRange = [[SCIDoubleRange alloc] initWithMin:-GrowBy max:VisibleRangeMax + GrowBy];
    
    id<ISCIAxis> yAxis = [SCINumericAxis new];
    yAxis.autoRange = SCIAutoRange_Always;
    
    _ds1 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    _ds1.fifoCapacity = FifoCapacicty;
    _ds2 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    _ds2.fifoCapacity = FifoCapacicty;
    _ds3 = [[SCIXyDataSeries alloc] initWithXType:SCIDataType_Double yType:SCIDataType_Double];
    _ds3.fifoCapacity = FifoCapacicty;

    SCIFastLineRenderableSeries *rSeries1 = [SCIFastLineRenderableSeries new];
    rSeries1.dataSeries = _ds1;
    rSeries1.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFF4083B7 thickness:2];
    
    SCIFastLineRenderableSeries *rSeries2 = [SCIFastLineRenderableSeries new];
    rSeries2.dataSeries = _ds2;
    rSeries2.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFFFFA500 thickness:2];
    
    SCIFastLineRenderableSeries *rSeries3 = [SCIFastLineRenderableSeries new];
    rSeries3.dataSeries = _ds3;
    rSeries3.strokeStyle = [[SCISolidPenStyle alloc] initWithColorCode:0xFFE13219 thickness:2];
    
    [SCIUpdateSuspender usingWithSuspendable:self.surface withBlock:^{
        [self.surface.xAxes add:xAxis];
        [self.surface.yAxes add:yAxis];
        [self.surface.renderableSeries add:rSeries1];
        [self.surface.renderableSeries add:rSeries2];
        [self.surface.renderableSeries add:rSeries3];
    }];
    
    _timer = [NSTimer scheduledTimerWithTimeInterval:TimeInterval / 1000.0 target:self selector:@selector(updateData:) userInfo:nil repeats:YES];
    _isRunning = YES;
}

- (void)updateData:(NSTimer *)timer {
    if (!_isRunning) return;
    
    double y1 = 3.0 * sin(((2 * M_PI) * 1.4) * _t) + [SCDRandomUtil nextDouble] * 0.5;
    double y2 = 2.0 * cos(((2 * M_PI) * 0.8) * _t) + [SCDRandomUtil nextDouble] * 0.5;
    double y3 = 1.0 * sin(((2 * M_PI) * 2.2) * _t) + [SCDRandomUtil nextDouble] * 0.5;
    
    [_ds1 appendX:@(_t) y:@(y1)];
    [_ds2 appendX:@(_t) y:@(y2)];
    [_ds3 appendX:@(_t) y:@(y3)];
    
    _t += OneOverTimeInterval;

    id<ISCIAxis> xAxis = [self.surface.xAxes itemAt:0];
    if (_t > VisibleRangeMax) {
        [xAxis.visibleRange setDoubleMinTo:xAxis.visibleRange.minAsDouble + OneOverTimeInterval maxTo:xAxis.visibleRange.maxAsDouble + OneOverTimeInterval];
    }
}

- (void)resetChart {
    [SCIUpdateSuspender usingWithSuspendable:self.surface withBlock:^{
        [self->_ds1 clear];
        [self->_ds2 clear];
        [self->_ds3 clear];
    }];
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    
    [_timer invalidate];
    _timer = nil;
}

@end

// FIFOSpeedTestSciChart.swift

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2019. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// FifoScrollingChartView.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.
//******************************************************************************

private let FifoCapacicty: Int = 50
private let TimeInterval = 30.0
private let OneOverTimeInterval = 1.0 / 30
private let VisibleRangeMax = 50.0 * 1.0 / 30.0
private let GrowBy = 50.0 * 1.0 / 30.0 * 0.1

class FifoScrollingChartView: SCDSingleChartViewController<SCIChartSurface> {
    
    private var _timer: Timer?
    private var _ds1: SCIXyDataSeries!
    private var _ds2: SCIXyDataSeries!
    private var _ds3: SCIXyDataSeries!
    
    private var _t = 0.0
    private var _isRunning = false
    
    override var associatedType: AnyClass { return SCIChartSurface.self }
    
    override func provideExampleSpecificToolbarItems() -> [ISCDToolbarItem] {
        return [SCDToolbarButtonsGroup(toolbarItems: [
            SCDToolbarButton(title: "Start", image: SCIImage(named: "chart.play"), andAction: { [weak self] in self?._isRunning = true }),
            SCDToolbarButton(title: "Pause", image: SCIImage(named: "chart.pause"), andAction: { [weak self] in self?._isRunning = false }),
            SCDToolbarButton(title: "Stop", image: SCIImage(named: "chart.stop"), andAction: { [weak self] in
                self?._isRunning = false
                self?.resetChart()
            })
        ])]
    }
    
    override func initExample() {
        let xAxis = SCINumericAxis()
        xAxis.autoRange = .never
        xAxis.visibleRange = SCIDoubleRange.init(min: -GrowBy, max: VisibleRangeMax + GrowBy)
        
        let yAxis = SCINumericAxis()
        yAxis.autoRange = .always

        _ds1 = SCIXyDataSeries(xType: .double, yType: .double)
        _ds1.fifoCapacity = FifoCapacicty
        _ds2 = SCIXyDataSeries(xType: .double, yType: .double)
        _ds2.fifoCapacity = FifoCapacicty
        _ds3 = SCIXyDataSeries(xType: .double, yType: .double)
        _ds3.fifoCapacity = FifoCapacicty
        
        let rSeries1 = SCIFastLineRenderableSeries()
        rSeries1.dataSeries = _ds1
        rSeries1.strokeStyle = SCISolidPenStyle(color: 0xFF4083B7, thickness: 2)
        
        let rSeries2 = SCIFastLineRenderableSeries()
        rSeries2.dataSeries = _ds2
        rSeries2.strokeStyle = SCISolidPenStyle(color: 0xFFFFA500, thickness: 2)
        
        let rSeries3 = SCIFastLineRenderableSeries()
        rSeries3.dataSeries = _ds3
        rSeries3.strokeStyle = SCISolidPenStyle(color: 0xFFE13219, thickness: 2)
        
        SCIUpdateSuspender.usingWith(surface) {
            self.surface.xAxes.add(xAxis)
            self.surface.yAxes.add(yAxis)
            self.surface.renderableSeries.add(rSeries1)
            self.surface.renderableSeries.add(rSeries2)
            self.surface.renderableSeries.add(rSeries3)
        }
        
        _timer = Timer.scheduledTimer(timeInterval: TimeInterval / 1000, target: self, selector: #selector(updateData), userInfo: nil, repeats: true)
        _isRunning = true
    }
    
    @objc func updateData(_ timer: Timer) {
        if (!_isRunning) { return }
        
        let y1: Double = 3.0 * sin(((2 * .pi) * 1.4) * _t) + SCDRandomUtil.nextDouble() * 0.5
        let y2: Double = 2.0 * cos(((2 * .pi) * 0.8) * _t) + SCDRandomUtil.nextDouble() * 0.5
        let y3: Double = 1.0 * sin(((2 * .pi) * 2.2) * _t) + SCDRandomUtil.nextDouble() * 0.5
        
        _ds1.append(x: _t, y: y1)
        _ds2.append(x: _t, y: y2)
        _ds3.append(x: _t, y: y3)
        
        _t += OneOverTimeInterval;
        
        let xAxis = surface.xAxes.item(at: 0)
        if (_t > VisibleRangeMax) {
            xAxis.visibleRange.setDoubleMinTo(xAxis.visibleRange.minAsDouble + OneOverTimeInterval, maxTo: xAxis.visibleRange.maxAsDouble + OneOverTimeInterval)
        }
    }
    
    fileprivate func resetChart() {
        SCIUpdateSuspender.usingWith(surface) {
            self._ds1.clear()
            self._ds2.clear()
            self._ds3.clear()
        }
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        
        _timer?.invalidate()
        _timer = nil
    }
}

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