#12770 fix ios build

ios/Runner/ScannerViewController.swift

@@ -32,7 +32,7 @@ import ZXingObjC
     
     var captureSizeTransform: CGAffineTransform?
     var buttonState: ButtonState = .card
-    var platformChannel: FlutterMethodChannel?
+    @objc var platformChannel: FlutterMethodChannel?
     var strings = [String:String]()
     
     let scanRectView = UIView()
@@ -46,7 +46,7 @@ import ZXingObjC
         super.init(coder: aDecoder)
     }
     
-    init(strings: [String: String]) {
+    @objc init(strings: [String: String]) {
         super.init(nibName: nil, bundle: nil)
         strings.forEach { (k,v) in self.strings[k] = v }
     }
@@ -131,17 +131,17 @@ import ZXingObjC
         settingsButton.addTarget(self, action: #selector(ScannerViewController.settingsTouch), for: .touchUpInside)
     }
     
-    func hideKeyboard() {
+    @objc func hideKeyboard() {
         view.endEditing(false)
     }
     
-    func buttonTouch() {
+    @objc func buttonTouch() {
         setButtonState()
         searchType.setImage(self.buttonState.icon, for: .normal)
         textField.placeholder = self.getInputHint()
     }
     
-    func settingsTouch() {
+    @objc func settingsTouch() {
         dropDown.show()
     }