iOS & macOS Charting Documentation - SciChart iOS & macOS Charts SDK v4.x

The SCIExtendedLineAnnotation

The SCIExtendedLineAnnotation is a specialized line annotation for iOS charts that can extend infinitely in one or both directions beyond its defined endpoints. It is commonly used in trading and technical analysis to project trendlines, support/resistance levels, or extended guides across the chart surface.

Extended Line Annotation

NOTE: Examples of the Annotations usage can be found in the SciChart iOS Examples Suite as well as on [GitHub]

Trading Annotations - Obj-C/Swift

Structure and Points

The SCIExtendedLineAnnotation is defined by two anchor points:

Point 1 (Start): The starting anchor of the line.
Point 2 (End): The ending anchor of the line.

Behavior

The line is drawn between Point 1 and Point 2.
Depending on the extendStart and extendEnd flags, the line may be projected infinitely beyond either or both anchor points.
The four extension modes are summarized in the table below:

extendStart	extendEnd	Behavior
YES	YES	Line extends infinitely in both directions.
NO	YES	Line extends infinitely forward from the end point only.
YES	NO	Line extends infinitely backward from the start point only.
NO	NO	Line is drawn only between the two anchor points (default line).

The SCIExtendedLineAnnotation can be configured using the properties listed in the table below:

Field	Description
`SCIExtendedLineAnnotation.extendStart`	When YES, the line is projected infinitely backward beyond the start point.
`SCIExtendedLineAnnotation.extendEnd`	When YES, the line is projected infinitely forward beyond the end point.

Points for a SCIExtendedLineAnnotation are defined using the set(x1:), set(y1:), set(x2:), set(y2:) methods inherited from SCILineAnnotationBase. The extension direction is then controlled independently via the extendStart and extendEnd flags.

NOTE: To learn more about Annotations in general - please see the Common Annotation Features article.

Create an ExtendedLineAnnotation

A SCIExtendedLineAnnotation can be added onto a chart using the following code:

// Assume a surface has been created and configured somewhere
id surface;

// Infinite Line: extends in both directions across the entire chart
SCIExtendedLineAnnotation *extendedLine = [SCIExtendedLineAnnotation new];
[extendedLine setX1:@10];
[extendedLine setY1:@11600];
[extendedLine setX2:@100];
[extendedLine setY2:@12400];

// Extend in both directions
extendedLine.extendStart = YES;
extendedLine.extendEnd = YES;

// Enable interaction
extendedLine.isEditable = YES;
extendedLine.stroke = [[SCISolidPenStyle alloc] initWithColorCode:0xFFFFFFFF thickness:3.0];

// Forward Ray: extends the line beyond the end point only
SCIExtendedLineAnnotation *forwardLine = [SCIExtendedLineAnnotation new];
[forwardLine setX1:@64];
[forwardLine setY1:@12000];
[forwardLine setX2:@70];
[forwardLine setY2:@11600];

// Extend forward beyond x2 only
forwardLine.extendStart = NO;
forwardLine.extendEnd = YES;

// Enable interaction
forwardLine.isEditable = YES;
forwardLine.stroke = [[SCISolidPenStyle alloc] initWithColorCode:0xFFFFFFFF thickness:3.0];

// Backward Ray: extends the line behind the start point only
SCIExtendedLineAnnotation *backwardLine = [SCIExtendedLineAnnotation new];
[backwardLine setX1:@30];
[backwardLine setY1:@12200];
[backwardLine setX2:@64];
[backwardLine setY2:@12100];

// Extend backward behind x1, do not extend forward
backwardLine.extendStart = YES;
backwardLine.extendEnd = NO;

// Enable interaction
backwardLine.isEditable = YES;
backwardLine.stroke = [[SCISolidPenStyle alloc] initWithColorCode:0xFFFFFFFF thickness:3.0];

// Add to chart surface
[self.surface.annotations addAll:extendedLine, backwardLine, forwardLine, nil];

// Assume a surface has been created and configured somewhere
let surface: ISCIChartSurface

// Infinite Line: extends in both directions across the entire chart
let extendedLine = SCIExtendedLineAnnotation()
extendedLine.set(x1: 10)
extendedLine.set(y1: 11600)
extendedLine.set(x2: 100)
extendedLine.set(y2: 12400)

// Extend in both directions
extendedLine.extendStart = true
extendedLine.extendEnd = true
            
// Enable interaction
extendedLine.isEditable = true
extendedLine.stroke = SCISolidPenStyle(color: 0xFFFFFFFF, thickness: 3)
            
// Forward Ray: extends the line beyond the end point only
let forwardLine = SCIExtendedLineAnnotation()
forwardLine.set(x1: 64)
forwardLine.set(y1: 12000)
forwardLine.set(x2: 70)
forwardLine.set(y2: 11600)
            
// Extend forward beyond x2 only
forwardLine.extendStart = false
forwardLine.extendEnd = true
            
// Enable interaction
forwardLine.isEditable = true
forwardLine.stroke = SCISolidPenStyle(color: 0xFFFFFFFF, thickness: 3)

// Backward Ray: extends the line behind the start point only
let backwardLine = SCIExtendedLineAnnotation()
backwardLine.set(x1: 30)
backwardLine.set(y1: 12200)
backwardLine.set(x2: 64)
backwardLine.set(y2: 12100)
            
// Extend backward behind x1, do not extend forward
backwardLine.extendStart = true
backwardLine.extendEnd = false
            
// Enable interaction
backwardLine.isEditable = true
backwardLine.stroke = SCISolidPenStyle(color: 0xFFFFFFFF, thickness: 3)
            
// Add to chart surface
self.surface.annotations.add(items: extendedLine, backwardLine, forwardLine)
            

NOTE: For interactive creation of SCIExtendedLineAnnotation, use the corresponding annotation creation modifier SCIExtendedLineCreationModifier available in SciChart iOS.

NOTE: To learn more about other Annotation Types, available out of the box in SciChart, please find the comprehensive list in the Annotation APIs article.