Enable SwiftLint rule 'weak_delegate' and fix all violations

.swiftlint.yml

@@ -192,7 +192,7 @@ whitelist_rules:
   - vertical_whitespace_closing_braces
   - vertical_whitespace_opening_braces
   - void_return
-#  - weak_delegate
+  - weak_delegate
   - xct_specific_matcher
   - xctfail_message
   - yoda_condition

pass/Controllers/QRScannerController.swift

@@ -26,7 +26,7 @@ class QRScannerController: UIViewController, AVCaptureMetadataOutputObjectsDeleg
 
     let supportedCodeTypes = [AVMetadataObject.ObjectType.qr]
 
-    var delegate: QRScannerControllerDelegate?
+    weak var delegate: QRScannerControllerDelegate?
 
     override func viewDidLoad() {
         super.viewDidLoad()

pass/Views/FillPasswordTableViewCell.swift

@@ -16,11 +16,11 @@ protocol FillPasswordTableViewCellDelegate: AnyObject {
 
 class FillPasswordTableViewCell: UITableViewCell, ContentProvider {
     @IBOutlet var contentTextField: UITextField!
-    var delegate: FillPasswordTableViewCellDelegate?
-
     @IBOutlet var settingButton: UIButton!
     @IBOutlet var generateButton: UIButton!
 
+    weak var delegate: FillPasswordTableViewCellDelegate?
+
     override func awakeFromNib() {
         super.awakeFromNib()
         // Initialization code

pass/Views/SliderTableViewCell.swift

@@ -17,7 +17,7 @@ class SliderTableViewCell: UITableViewCell {
     private var checker: ((Int) -> Bool)!
     private var updater: ((Int) -> Void)!
 
-    private var delegate: PasswordSettingSliderTableViewCellDelegate!
+    private weak var delegate: PasswordSettingSliderTableViewCellDelegate!
 
     @IBAction
     private func handleSliderValueChange(_ sender: UISlider) {

pass/Views/SwitchTableViewCell.swift

@@ -15,7 +15,7 @@ class SwitchTableViewCell: UITableViewCell {
 
     private var updater: ((Bool) -> Void)!
 
-    private var delegate: PasswordSettingSliderTableViewCellDelegate!
+    private weak var delegate: PasswordSettingSliderTableViewCellDelegate!
 
     @IBAction
     private func switchValueChanged(_: Any) {