fix lint warnings

deltachat-ios/Controller/EditContactController.swift

@@ -28,7 +28,7 @@ class EditContactController: NewContactController {
     }
 
     @objc override func saveContactButtonPressed() {
-        dcContext.createContact(name: model.name, email: model.email)
+        _ = dcContext.createContact(name: model.name, email: model.email)
         coordinator?.navigateBack()
     }
 

deltachat-ios/Controller/EditGroupViewController.swift

@@ -77,7 +77,7 @@ class EditGroupViewController: UITableViewController, MediaPickerDelegate {
         if let groupImage = groupImage, let dcContext = coordinator?.dcContext {
             AvatarHelper.saveChatAvatar(dcContext: dcContext, image: groupImage, for: Int(chat.id))
         }
-        DcContext.getInstance().setChatName(chatId: chat.id, name: newName ?? "")
+        _ = DcContext.getInstance().setChatName(chatId: chat.id, name: newName ?? "")
         coordinator?.navigateBack()
     }
 

deltachat-ios/Controller/GroupChatDetailViewController.swift

@@ -391,7 +391,7 @@ extension GroupChatDetailViewController {
         if let userId = currentUser?.id {
             let alert = UIAlertController(title: String.localized("ask_leave_group"), message: nil, preferredStyle: .safeActionSheet)
             alert.addAction(UIAlertAction(title: String.localized("menu_leave_group"), style: .destructive, handler: { _ in
-                let _ = self.context.removeContactFromChat(chatId: self.chat.id, contactId: userId)
+                _ = self.context.removeContactFromChat(chatId: self.chat.id, contactId: userId)
                 self.editBarButtonItem.isEnabled = false
                 self.updateGroupMembers()
             }))

deltachat-ios/DC/Wrapper.swift

@@ -361,7 +361,7 @@ class DcContext {
     }
 
     func imexHasBackup(filePath: String) -> String? {
-        var file: String? = nil
+        var file: String?
         if let cString = dc_imex_has_backup(contextPointer, filePath) {
             file = String(cString: cString)
             dc_str_unref(cString)