Instance Property


Returns the alpha information associated with the context, which indicates how a bitmap context handles the alpha component.


var alphaInfo: CGImageAlphaInfo { get }



A bitmap context.

Return Value

A bitmap information constant. If the specified context is not a bitmap context, CGImageAlphaInfo.none is returned.


Every bitmap context contains an attribute that specifies whether the bitmap contains an alpha component, and how it is generated. The alpha component determines the opacity of a pixel when it is drawn.

See Also

Managing a Bitmap Graphics Context

var bitmapInfo: CGBitmapInfo

Obtains the bitmap information associated with a bitmap graphics context.

var bitsPerComponent: Int

Returns the bits per component of a bitmap context.

var bitsPerPixel: Int

Returns the bits per pixel of a bitmap context.

var bytesPerRow: Int

Returns the bytes per row of a bitmap context.

var colorSpace: CGColorSpace?

Returns the color space of a bitmap context.

var data: UnsafeMutableRawPointer?

Returns a pointer to the image data associated with a bitmap context.

var height: Int

Returns the height in pixels of a bitmap context.

var width: Int

Returns the width in pixels of a bitmap context.

func makeImage() -> CGImage?

Creates and returns a CGImage from the pixel data in a bitmap graphics context.