Loading and calling AppKit

[aplavin]

I took a code snippet calling AppKit from an old version of ObjectiveC.jl and adapted it to the current one. Specifically, I needed [NSApp setActivationPolicy].
Not sure if it looks reasonable already or should be written better? I'm not really familiar with ObjectiveC itself...
Here's the code in question, seems very verbose:

using ObjectiveC: id, Object, NSString, NSObject, @objc, @objcwrapper
@objcwrapper NSApplication <: NSObject
function show_gl_icon_in_dock(show::Bool)
    path = "/System/Library/Frameworks/AppKit.framework"

    path = NSString(path)
    bundle = @objc [NSBundle bundleWithPath:path::id{NSString}]::id{Object}
    loaded = @objc [bundle::id{Object} load]::id{Object}

    NSApp = Base.bitcast(id{Object}, cglobal(:NSApp, Ptr{Cvoid}) |> unsafe_load)
    @objc [NSApplication sharedApplication]::id{Object}
    NSApplicationActivationPolicyRegular   = 0
    NSApplicationActivationPolicyAccessory = 1
    val = show ? NSApplicationActivationPolicyRegular : NSApplicationActivationPolicyAccessory
    @objc [NSApp::id{Object} setActivationPolicy:val::Int]::id{Object}
end

(at https://github.com/JuliaAPlavin/MakieExtra.jl/blob/000000006524e0a0729128be0a0681f081cff0aa/src/MakieExtra.jl#L69-L85)