Merge pull request #406 from p-mazhnik/pavel/ios-torch

fix(ios): fix torch

@@ -22,10 +22,10 @@ Features:
 * Added a new `placeholderBuilder` function to the `MobileScanner` widget to customize the preview placeholder.
 * Added `autoStart` parameter to MobileScannerController(). If set to false, controller won't start automatically.
 * Added `hasTorch` function on MobileScannerController(). After starting the controller, you can check if the device has a torch.
+* [iOS] Support `torchEnabled` parameter from MobileScannerController() on iOS
 * [Web] Added ability to use custom barcode scanning js libraries 
   by extending `WebBarcodeReaderBase` class and changing `barCodeReader` property in `MobileScannerWebPlugin`
 
-
 Fixes:
 * Fixes the missing gradle setup for the Android project, which prevented gradle sync from working.
 * Fixes `MobileScannerController.stop()` throwing when already stopped.
@@ -35,6 +35,7 @@ Fixes:
 * Fixes the `MobileScanner` preview depending on all attributes of `MediaQueryData`.
   Now it only depends on its layout constraints.
 * Fixed a potential crash when the scanner is restarted due to the app being resumed.
+* [iOS] Fix crash when changing torch state
   
 ## 3.0.0-beta.2
 Breaking changes:

@@ -12,6 +12,7 @@ import MLKitVision
 import MLKitBarcodeScanning
 
 typealias MobileScannerCallback = ((Array<Barcode>?, Error?, UIImage) -> ())
+typealias TorchModeChangeCallback = ((Int?) -> ())
 
 public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate, FlutterTexture {
     /// Capture session of the camera
@@ -32,6 +33,9 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
     /// When results are found, this callback will be called
     let mobileScannerCallback: MobileScannerCallback
 
+    /// When torch mode is changes, this callback will be called
+    let torchModeChangeCallback: TorchModeChangeCallback
+
     /// If provided, the Flutter registry will be used to send the output of the CaptureOutput to a Flutter texture.
     private let registry: FlutterTextureRegistry?
 
@@ -43,9 +47,10 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
 
     var detectionSpeed: DetectionSpeed = DetectionSpeed.noDuplicates
 
-    init(registry: FlutterTextureRegistry?, mobileScannerCallback: @escaping MobileScannerCallback) {
+    init(registry: FlutterTextureRegistry?, mobileScannerCallback: @escaping MobileScannerCallback, torchModeChangeCallback: @escaping TorchModeChangeCallback) {
         self.registry = registry
         self.mobileScannerCallback = mobileScannerCallback
+        self.torchModeChangeCallback = torchModeChangeCallback
         super.init()
     }
 
@@ -127,17 +132,6 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
             throw MobileScannerError.noCamera
         }
 
-        // Enable the torch if parameter is set and torch is available
-        if (device.hasTorch && device.isTorchAvailable) {
-            do {
-                try device.lockForConfiguration()
-                device.torchMode = torch
-                device.unlockForConfiguration()
-            } catch {
-                throw MobileScannerError.torchError(error)
-            }
-        }
-
         device.addObserver(self, forKeyPath: #keyPath(AVCaptureDevice.torchMode), options: .new, context: nil)
         captureSession.beginConfiguration()
 
@@ -169,6 +163,13 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         }
         captureSession.commitConfiguration()
         captureSession.startRunning()
+        // Enable the torch if parameter is set and torch is available
+        // torch should be set after 'startRunning' is called
+        do {
+            try toggleTorch(torch)
+        } catch {
+            print("Failed to set initial torch state.")
+        }
         let dimensions = CMVideoFormatDescriptionGetDimensions(device.activeFormat.formatDescription)
 
         return MobileScannerStartParameters(width: Double(dimensions.height), height: Double(dimensions.width), hasTorch: device.hasTorch, textureId: textureId)
@@ -198,12 +199,26 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         if (device == nil) {
             throw MobileScannerError.torchWhenStopped
         }
-        do {
-            try device.lockForConfiguration()
-            device.torchMode = torch
-            device.unlockForConfiguration()
-        } catch {
-            throw MobileScannerError.torchError(error)
+        if (device.hasTorch && device.isTorchAvailable) {
+            do {
+                try device.lockForConfiguration()
+                device.torchMode = torch
+                device.unlockForConfiguration()
+            } catch {
+                throw MobileScannerError.torchError(error)
+            }
+        }
+    }
+
+    // Observer for torch state
+    public override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
+        switch keyPath {
+        case "torchMode":
+            // off = 0; on = 1; auto = 2;
+            let state = change?[.newKey] as? Int
+            torchModeChangeCallback(state)
+        default:
+            break
         }
     }
 

@@ -55,6 +55,8 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
             } else if (error != nil){
                 barcodeHandler.publishEvent(["name": "error", "data": error!.localizedDescription])
             }
+        }, torchModeChangeCallback: { torchState in
+            barcodeHandler.publishEvent(["name": "torchState", "data": torchState])
         })
         self.barcodeHandler = barcodeHandler
         super.init()
@@ -201,16 +203,4 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
         })
         result(nil)
     }
-    
-    /// Observer for torch state
-    public override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
-        switch keyPath {
-        case "torchMode":
-            // off = 0; on = 1; auto = 2;
-            let state = change?[.newKey] as? Int
-            barcodeHandler.publishEvent(["name": "torchState", "data": state])
-        default:
-            break
-        }
-    }
 }