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

The SCITextAnnotation

The SCITextAnnotation allows to place a piece of text at a specific location on a chart:

Text Annotation

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

Annotations are Easy - Obj-C/Swift, Xamarin.iOS

Interaction with Annotations - Obj-C/Swift, Xamarin.iOS

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

Property	Description
`SCITextAnnotationBase.text`	Specifies the text for an annotation.
`SCITextAnnotationBase.attributedText`	Specifies the attributed text for your label. In this case, the `text` property will be ignored.
`SCITextAnnotationBase.fontStyle`	Determines the appearance of the text via the `SCIFontStyle` object. Please refer to the Styling and Theming article to learn more.
`SCITextAnnotationBase.alignment`	Specifies a text alignment with `SCIAlignment`.
`SCITextAnnotationBase.padding`	Defines the padding around the text
`SCITextAnnotationBase.canEditText`	When set to `YES` - allows to modify the text in run-time after selecting an annotation. See the Edit SCITextAnnotation in Run-Time section.
`SCITextAnnotationBase.rotationAngle`	Rotates an annotation through the specified angle in degrees.

Position of the SCITextAnnotation is defined by the X1 or Y1 coordinate, depending on the axis. Those values can be accessed via the ISCIAnnotation.x1 and ISCIAnnotation.y1 properties.

NOTE: The xAxisId and yAxisId must be supplied if you have axis with non-default Axis Ids, e.g. in multi-axis scenario.

Also, because SCITextAnnotation is derived from the SCIAnchorPointAnnotation it can be aligned relative to the X1 or Y1 coordinate by setting the Anchor Points. For more information about the Anchor Points - refer to the corresponding section Annotations APIs article.

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

Create a SCITextAnnotation

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

// Assume a surface has been created and configured somewhere
id<ISCIChartSurface> surface;
// Create SCICustomAnnotation instance
SCITextAnnotation *textAnnotation = [SCITextAnnotation new];
// Set the text
textAnnotation.text = @“Text can be Rotated”;
// Specify a SCIFontStyle for the text
textAnnotation.fontStyle = [[SCIFontStyle alloc] initWithFontSize:20 andTextColorCode:0xBBFC9C29];
// Specify rotation Angle in Degrees if needed
textAnnotation.rotationAngle = -30;
// Specify a desired position
textAnnotation.x1 = @(20);
textAnnotation.y1 = @(14);
// Allow to interact with the annotation in run-time
textAnnotation.isEditable = YES;
// In a multi-axis scenario, specify the XAxisId and YAxisId
textAnnotation.xAxisId = BottomAxisId;
textAnnotation.yAxisId = LeftAxisId;
// Add the annotation to the Annotations collection of the surface
[self.surface.annotations add:textAnnotation];

// Assume a surface has been created and configured somewhere
let surface: ISCIChartSurface
// Create SCICustomAnnotation instance
let textAnnotation = SCITextAnnotation()
// Set the text
textAnnotation.text = “Text can be Rotated”
// Specify a SCIFontStyle for the text
textAnnotation.fontStyle = = SCIFontStyle(fontSize: 20, andTextColorCode: 0xBBFC9C29)
// Specify rotation Angle in Degrees if needed
textAnnotation.rotationAngle = -30
// Specify a desired position
textAnnotation.set(x1: 20)
textAnnotation.set(y1: 14)
// Allow to interact with the annotation in run-time
textAnnotation.isEditable = true
// In a multi-axis scenario, specify the XAxisId and YAxisId
textAnnotation.xAxisId = BottomAxisId
textAnnotation.yAxisId = LeftAxisId
// Add the annotation to the Annotations collection of the surface
self.surface.annotations.add(textAnnotation)

// Assume a surface has been created and configured somewhere
IISCIChartSurface surface;
// Create SCICustomAnnotation instance
var textAnnotation = new SCITextAnnotation();
// Set the text
textAnnotation.Text = “Text can be Rotated”;
// Specify a SCIFontStyle for the text
textAnnotation.FontStyle = new SCIFontStyle(20, 0xBBFC9C29);
// Specify rotation Angle in Degrees if needed
textAnnotation.RotationAngle = -30;
// Specify a desired position
textAnnotation.X1Value = 20;
textAnnotation.Y1Value = 14;
// Allow to interact with the annotation in run-time
textAnnotation.IsEditable = true;
// In a multi-axis scenario, specify the XAxisId and YAxisId
textAnnotation.XAxisId = BottomAxisId;
textAnnotation.YAxisId = LeftAxisId;
// Add the annotation to the Annotations collection of the surface
Surface.Annotations.Add(textAnnotation);

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.

Edit SCITextAnnotation in Run-Time

The SCITextAnnotation can be edited in run-time. To turn that on - just set SCITextAnnotationBase.canEditText to YES on your annotation.

Please see the code snippet and result below:

SCITextAnnotation *editTextAnnotation = [SCITextAnnotation new];
editTextAnnotation.isEditable = YES;
editTextAnnotation.canEditText = YES;
editTextAnnotation.xAxisId = BottomAxisId;
editTextAnnotation.yAxisId = LeftAxisId;
editTextAnnotation.x1 = @(80);
editTextAnnotation.y1 = @(14);
editTextAnnotation.text = @“and edited …”;
editTextAnnotation.fontStyle = [[SCIFontStyle alloc] initWithFontSize:20 andTextColor:UIColor.yellowColor];

let editTextAnnotation = SCITextAnnotation()
editTextAnnotation.isEditable = true
editTextAnnotation.canEditText = true
editTextAnnotation.xAxisId = BottomAxisId
editTextAnnotation.yAxisId = LeftAxisId
editTextAnnotation.set(x1: 80)
editTextAnnotation.set(y1: 14)
editTextAnnotation.text = “and edited …”
editTextAnnotation.fontStyle = SCIFontStyle(fontSize: 20, andTextColor: .yellow)

var editTextAnnotation = new SCITextAnnotation();
editTextAnnotation.IsEditable = true;
editTextAnnotation.CanEditText = true;
editTextAnnotation.XAxisId = BottomAxisId;
editTextAnnotation.YAxisId = LeftAxisId;
editTextAnnotation.X1Value = 80;
editTextAnnotation.Y1Value = 14;
editTextAnnotation.Text = “and edited …”;
editTextAnnotation.FontStyle = new SCIFontStyle(20, UIColor.Yellow);

NOTE: Be aware, if you use canEditText (allows edit text in run-time) in conjunction with isEditable (allows drag annotation over that chart), you will need to perform 2 taps - first one to select annotation, and only after that - tap to enter editing.