This answer says the block is more efficient than manually managing NSAutoreleasePool objects: https://stackoverflow.com/a/12448176

This answer looks like a better overview of what the runtime is doing: https://stackoverflow.com/a/21010442

The @autoreleasepool block seems equivalent to this:

    ctx = _objc_autoreleasePoolPush()
    defer _objc_autoreleasePoolPop(ctx)

You could maybe provide sugar for it like this: https://play.golang.org/p/dljXN3BdEGr