Avoid thread explosion

Vector Artwork Pipeline

Vector Artwork Optimizations

• Xcode raterizes artwork for relevant scale factors while compiling.
• Prerasterized artwork used when image is drawn at natural size.
• If artwork has fixed sizes, use multiple image assets instead of relying on vector rasterization.

Custom Drawing vs UIImageView

• Do not override UIView.draw() when you make a customized view.
  This is an very inefficient way.
• Use UIImageView.draw() because ‘Decoded Image’ is better than ‘Backing store’

Backing Store Memory Costs

• Proportional to pixel size of view
• Element size grows to accommodate color range used by drawing
• Setting CALayer.contentsFormat opts out
• Update layerWillDraw(_:) implementations

Reducing Backing Store Use

Drawing Off-Screen

• Use UIGrahpicsImageRenderer to create and draw to an imag buffer
• Supports, Wide Color, unlike UIGraphicBeginContext( )
• Combine with UIImageView for efficient offscreen rendering
• Set prefersExtendedRange on UIGraphicsImageRendererFormat for direct control (new)
• UIImage.imageRendererFormat may offer an intermediate representation (new)

Advanced Image Effects

Core Image

• For realtime effects
• UIImageView renders CIImage efficiently. UIImage.init(ciImage: )

Interfacing with other frameworks

• CVPixelBuffer ( Data → Metal, Vision, Accelerate )
• Use the best initializer — don’t unwind work that’s already been done
• Guard against moving work GPU ↔ CPU
• Ensure buffers are correct format for Accelerate