Metal 4 Presentation & Frame Pacing

Overview

Metal 4 splits the cmd-buffer-level [cmd presentDrawable:] into a queue-level sequence: [queue waitForDrawable:] before commit, [queue signalDrawable:] after commit, and [drawable present]. The conceptual flow — acquire drawable, encode, present, submit — is unchanged; only the API surface is more explicit. MTL4CommandBuffer does not expose presentDrawable:, so any code path using MTL4CommandQueue must use the queue-level form. Code paths still using the Metal 3 MTLCommandQueue keep [cmd presentDrawable:] and remain correct in a Metal 4 app.

Ownership

Owns:

• Drawable lifecycle (nextDrawable, waitForDrawable, signalDrawable, present)
• CAMetalLayer configuration and properties
• Vsync semantics (displaySyncEnabled, presentAfterMinimumDuration:)
• CAMetalDisplayLink API basics; variable refresh rate detection
• HDR/EDR layer configuration; pixel format ↔ colorspace pairing
• Direct-to-display vs composited presentation rules
• Drawable residency set (the layer-owned read-only residencySet)
• Apply-after-present rule