Hide cellular toggle on non-cellular devices

Many iPads don’t have a cellular connection. It’s a little confusing to show the cellular toggle when it doesn’t apply.

Unfortunately, there’s no good (undeprecated) API for checking this. I’ve used an approach of listing the network interfaces and looking for the cellular one, but it’s undocumented and might not always work.

OTOH, this isn’t a critical feature, so we can keep an eye on it.

Author: joshheald

Modules/Sources/PointOfSale/Presentation/Settings/POSSettingsLocalCatalogDetailView.swift

@@ -18,7 +18,9 @@ struct POSSettingsLocalCatalogDetailView: View {
                 ScrollView {
                     VStack(spacing: POSSpacing.medium) {
                         catalogStatus
-                        managingDataUsage
+                        if viewModel.deviceHasCellularCapability {
+                            managingDataUsage
+                        }
                         manualCatalogUpdate
                     }
                     .padding(.horizontal, POSPadding.medium)

Modules/Sources/PointOfSale/Presentation/Settings/POSSettingsLocalCatalogViewModel.swift

@@ -2,6 +2,7 @@ import CocoaLumberjackSwift
 import Yosemite
 import Foundation
 import Storage
+import WooFoundation
 
 @Observable
 final class POSSettingsLocalCatalogViewModel {
@@ -11,6 +12,7 @@ final class POSSettingsLocalCatalogViewModel {
 
     private(set) var isLoading: Bool = false
     private(set) var isRefreshingCatalog: Bool = false
+    let deviceHasCellularCapability: Bool = CellularCapabilityChecker.deviceHasCellularCapability()
 
     var catalogRefreshError: POSIdentifiableErrorState? = nil
 

Modules/Sources/WooFoundation/Utilities/Connectivity/CellularCapabilityChecker.swift

@@ -0,0 +1,26 @@
+import Darwin
+
+public struct CellularCapabilityChecker {
+    public static func deviceHasCellularCapability() -> Bool {
+        var addrs: UnsafeMutablePointer<ifaddrs>?
+        guard getifaddrs(&addrs) == 0 else { return false }
+        defer { freeifaddrs(addrs) }
+
+        var cursor = addrs
+        while let addr = cursor {
+            guard let namePtr = addr.pointee.ifa_name else {
+                cursor = addr.pointee.ifa_next
+                continue
+            }
+
+            let name = String(cString: namePtr)
+            // This isn't a great check, but the alternatives are deprecated, and apparently it's commonly used.
+            // pdp_ip0 is the first cellular interface – it's not present if there's no cellular hardware.
+            if name == "pdp_ip0" {
+                return true
+            }
+            cursor = addr.pointee.ifa_next
+        }
+        return false
+    }
+}