Function capture_view 

pub unsafe fn capture_view(
    view: *mut c_void,
    width: u32,
    height: u32,
) -> Rendered

Capture any NSView into a width x height bitmap.

Some things SwiftUI draws never reach a hosting view’s own layer — a .toolbar is installed into the window’s titlebar, which is a sibling of the content view — so verifying them means capturing a different view than the one the root was set on. See capture_window.

Safety

view must be a live NSView.