Enable SwiftLint rule 'empty_string' and fix all violations

.swiftlint.yml

@@ -42,7 +42,7 @@ whitelist_rules:
   - empty_enum_arguments
   - empty_parameters
   - empty_parentheses_with_trailing_closure
-#  - empty_string
+  - empty_string
 #  - empty_xctest_method
   - enum_case_associated_values_count
   - expiring_todo

pass/Controllers/PasswordEditorTableViewController.swift

@@ -315,7 +315,7 @@ class PasswordEditorTableViewController: UITableViewController {
     private func insertScannedOTPFields(_ otpauth: String) {
         // update tableData
         var additionsString = ""
-        if let additionsPlainText = (tableData[additionsSection][0][PasswordEditorCellKey.content] as? String)?.trimmed, additionsPlainText != "" {
+        if let additionsPlainText = (tableData[additionsSection][0][PasswordEditorCellKey.content] as? String)?.trimmed, !additionsPlainText.isEmpty {
             additionsString = additionsPlainText + "\n" + otpauth
         } else {
             additionsString = otpauth

pass/Controllers/PasswordsViewController.swift

@@ -580,7 +580,7 @@ class PasswordsViewController: UIViewController, UITableViewDataSource, UITableV
 
     func filterContentForSearchText(searchText: String, scope: SearchBarScope = .all) {
         var entries: [PasswordTableEntry] = scope == .all ? passwordsTableAllEntries : passwordsTableEntries
-        if searchController.isActive, searchController.searchBar.text != "" {
+        if searchController.isActive, let searchBarText = searchController.searchBar.text, !searchBarText.isEmpty {
             entries = entries.filter { $0.match(searchText) }
         }
         reloadTableView(data: entries)

pass/Views/LabelTableViewCell.swift

@@ -43,7 +43,7 @@ class LabelTableViewCell: UITableViewCell {
                 if isReveal {
                     contentLabel.attributedText = Utils.attributedPassword(plainPassword: content)
                 } else {
-                    if content == "" {
+                    if content.isEmpty {
                         contentLabel.text = ""
                     } else {
                         contentLabel.text = Globals.passwordDots
@@ -163,7 +163,7 @@ class LabelTableViewCell: UITableViewCell {
 
         switch type {
         case .password:
-            if let content = cellData?.content, content != "" {
+            if let content = cellData?.content, !content.isEmpty {
                 // password button
                 passwordDisplayButton = UIButton(type: .system)
                 passwordDisplayButton!.frame = CGRect(x: 0, y: 0, width: width, height: height)