Skip to main content
Desktop assignment lets you bind profiles to specific macOS desktops (Spaces). When you swipe to a desktop, HopTab automatically activates the assigned profile and updates your pinned apps.

​
How it works

Each macOS Space has a unique numeric ID. HopTab maintains a mapping from Space IDs to profile IDs. When the active Space changes, HopTab looks up the assigned profile and switches to it automatically. The mapping is stored in PinnedAppsStore.swift:14: 
/// Maps Space ID (Int) → Profile ID (UUID string). Persisted in UserDefaults.
@Published var spaceMapping: [Int: UUID] = [:]

​
Assigning profiles to desktops

1

Swipe to the target desktop

Use Mission Control or a swipe gesture to navigate to the desktop you want to configure
2

Open Settings > Profiles

Click the HopTab menu bar icon and select Settings, then go to the Profiles tab
3

Assign the profile

Click “Assign to this desktop” next to the profile you want to activate on this Space
4

Repeat for other desktops

Swipe to other desktops and assign profiles as needed

​
Assigning implementation

When you click “Assign to this desktop”, HopTab calls assignProfileToCurrentSpace (PinnedAppsStore.swift:64-70): 
func assignProfileToCurrentSpace(profileId: UUID) {
    guard let spaceId = SpaceService.currentSpaceId else { return }
    // Remove any existing mapping for this profile (one profile per space)
    spaceMapping = spaceMapping.filter { $0.value != profileId }
    spaceMapping[spaceId] = profileId
    save()
}
Each profile can only be assigned to one desktop at a time. Assigning a profile to a new desktop automatically removes its previous assignment.

​
Automatic profile switching

HopTab listens for NSWorkspace.activeSpaceDidChangeNotification to detect when you switch desktops (AppState.swift:343-354): 
let spaceObserver = center.addObserver(
    forName: NSWorkspace.activeSpaceDidChangeNotification,
    object: nil,
    queue: .main
) { [weak self] _ in
    Task { @MainActor in
        self?.handleSpaceChange()
    }
}
When the notification fires, handleSpaceChange looks up the profile and activates it (AppState.swift:356-361): 
private func handleSpaceChange() {
    guard let spaceId = SpaceService.currentSpaceId,
          let profileId = store.profileForSpace(spaceId)
    else { return }
    store.setActiveProfile(id: profileId)
}

​
Getting the current Space ID

HopTab uses a private macOS API to get the currently active Space ID. The SpaceService wrapper (SpaceService.swift:10-16) calls CGSGetActiveSpace: 
static var currentSpaceId: Int? {
    let conn = CGSMainConnectionID()
    guard conn > 0 else { return nil }
    let spaceId = CGSGetActiveSpace(conn)
    guard spaceId > 0 else { return nil }
    return spaceId
}
The private API functions are declared using @_silgen_name (SpaceService.swift:22-27): 
@_silgen_name("CGSMainConnectionID")
private func CGSMainConnectionID() -> Int32

@_silgen_name("CGSGetActiveSpace")
private func CGSGetActiveSpace(_ cid: Int32) -> Int
Space IDs are session-local and can change after a reboot or when you add/remove desktops in Mission Control. If your assignments stop working, just reassign them — it only takes a few seconds.

​
Example workflow

Set up context-specific workspaces across multiple desktops:

Desktop 1: Coding

Profile: CodingApps: Xcode, Simulator, Terminal

Desktop 2: Design

Profile: DesignApps: Figma, Safari, Preview

Desktop 3: Communication

Profile: CommsApps: Slack, Mail, Calendar
Now when you swipe between desktops:
  • Swipe to Desktop 1 → HopTab activates the “Coding” profile
  • Press Option + Tab → cycle through Xcode, Simulator, Terminal
  • Swipe to Desktop 3 → HopTab switches to “Comms” profile
  • Press Option + Tab → now cycling through Slack, Mail, Calendar
Your workspace adapts automatically. No manual profile switching needed.

​
Looking up assignments

You can check which profile is assigned to a Space, or which Space is assigned to a profile:

​
Profile for a Space

func profileForSpace(_ spaceId: Int) -> UUID? {
    guard let profileId = spaceMapping[spaceId],
          profiles.contains(where: { $0.id == profileId })
    else { return nil }
    return profileId
}

​
Space for a profile

func spaceForProfile(_ profileId: UUID) -> Int? {
    spaceMapping.first { $0.value == profileId }?.key
}

​
Removing assignments

To unassign a profile from its desktop (PinnedAppsStore.swift:73-76): 
func unassignProfileFromSpace(profileId: UUID) {
    spaceMapping = spaceMapping.filter { $0.value != profileId }
    save()
}
When you delete a profile, any desktop assignments are automatically removed (PinnedAppsStore.swift:46-53): 
func deleteProfile(id: UUID) {
    profiles.removeAll { $0.id == id }
    spaceMapping = spaceMapping.filter { $0.value != id }
    if activeProfileId == id {
        activeProfileId = profiles.first?.id
    }
    save()
}

​
Persistence

The Space-to-profile mapping is saved to UserDefaults as a dictionary of strings (PinnedAppsStore.swift:148-149): 
let stringMap = Dictionary(uniqueKeysWithValues: spaceMapping.map { ("\($0.key)", $0.value.uuidString) })
UserDefaults.standard.set(stringMap, forKey: Self.spaceMappingKey)
On load, the string dictionary is converted back to [Int: UUID] (PinnedAppsStore.swift:154-161): 
if let stringMap = UserDefaults.standard.dictionary(forKey: Self.spaceMappingKey) as? [String: String] {
    spaceMapping = [:]
    for (spaceStr, profileStr) in stringMap {
        if let spaceId = Int(spaceStr), let profileId = UUID(uuidString: profileStr) {
            spaceMapping[spaceId] = profileId
        }
    }
}

Profiles

Learn how to create and manage profiles

App switching

Understand the app switcher behavior

Build docs developers (and LLMs) love

Get started for freeTalk to us