feat(ios): 新增iOS平台摄像头原生对焦插件适配

1. 新增iOS原生插件CameraFocusHelper，实现连续自动对焦和曝光控制
2. 适配iOS平台的扫码对焦逻辑，替换原生Unity的自动对焦实现
3. 新增跨平台自动对焦维护协程，区分iOS和其他平台的对焦处理逻辑
4. 优化扫码对焦体验，限制对焦范围为近距并开启低光增强

Assets/Plugins/iOS/CameraFocusHelper.mm

@@ -0,0 +1,69 @@
+#import <AVFoundation/AVFoundation.h>
+#import <UIKit/UIKit.h>
+
+extern "C" {
+
+    /// 启用连续自动对焦和自动曝光
+    void _EnableContinuousAutoFocus()
+    {
+        dispatch_async(dispatch_get_main_queue(), ^{
+            AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
+            if (!device) return;
+
+            NSError *error = nil;
+
+            // 锁定设备开始配置
+            if ([device lockForConfiguration:&error]) {
+
+                // 连续自动对焦模式（持续调整，适合扫描二维码）
+                if ([device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
+                    device.focusMode = AVCaptureFocusModeContinuousAutoFocus;
+                }
+
+                // 连续自动曝光
+                if ([device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
+                    device.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
+                }
+
+                // 对焦范围限制为近距（适合二维码）
+                if ([device respondsToSelector:@selector(setAutoFocusRangeRestriction:)]) {
+                    if ([device isAutoFocusRangeRestrictionSupported]) {
+                        device.autoFocusRangeRestriction = AVCaptureAutoFocusRangeRestrictionNear;
+                    }
+                }
+
+                // 启用低光增强（昏暗环境提高识别率）
+                if ([device respondsToSelector:@selector(setAutomaticallyEnablesLowLightBoostWhenAvailable:)]) {
+                    device.automaticallyEnablesLowLightBoostWhenAvailable = YES;
+                }
+
+                [device unlockForConfiguration];
+
+                NSLog(@"[CameraFocusHelper] 已启用连续自动对焦");
+            } else {
+                NSLog(@"[CameraFocusHelper] 锁定设备失败: %@", error.localizedDescription);
+            }
+        });
+    }
+
+    /// 触发一次自动对焦（用于手动点按时调用）
+    void _TriggerAutoFocus()
+    {
+        dispatch_async(dispatch_get_main_queue(), ^{
+            AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
+            if (!device) return;
+
+            NSError *error = nil;
+            if ([device lockForConfiguration:&error]) {
+                if ([device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
+                    device.focusMode = AVCaptureFocusModeAutoFocus;
+                }
+                if ([device isExposureModeSupported:AVCaptureExposureModeAutoExpose]) {
+                    device.exposureMode = AVCaptureExposureModeAutoExpose;
+                }
+                [device unlockForConfiguration];
+            }
+        });
+    }
+
+}

Assets/Scripts/UI/Pages/ConnectDevice/ScanQRcode.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using Kill.UI.Components;
 using UnityEngine;
 using UnityEngine.UI;
@@ -41,6 +42,14 @@ namespace Kill.UI.Pages
         public bool enableAutoFocus = true;
         [Tooltip("对焦间隔（秒）")]
         public float focusInterval = 1f;
+
+#if UNITY_IOS && !UNITY_EDITOR
+        [DllImport("__Internal")]
+        private static extern void _EnableContinuousAutoFocus();
+
+        [DllImport("__Internal")]
+        private static extern void _TriggerAutoFocus();
+#endif
         // 摄像头相关
         private WebCamTexture webCamTexture;
         private WebCamDevice currentDevice;
@@ -162,7 +171,14 @@ namespace Kill.UI.Pages
 
             // 等待摄像头启动
             yield return new WaitUntil(() => webCamTexture.width > 100);
-            webCamTexture.autoFocusPoint=new Vector2(0.5f,0.5f);
+
+            // iOS: 调用原生插件强制开启连续自动对焦
+#if UNITY_IOS && !UNITY_EDITOR
+            if (enableAutoFocus)
+            {
+                _EnableContinuousAutoFocus();
+            }
+#endif
             // 调整预览画面比例
             AdjustPreviewAspect();
             
@@ -170,6 +186,11 @@ namespace Kill.UI.Pages
             // 开始预览更新和扫描
             StartCoroutine(PreviewUpdateCoroutine());
             StartCoroutine(ScanCoroutine());
+            // 启动自动对焦维护协程（仅非 iOS 平台使用 autoFocusPoint，iOS 走原生插件）
+            if (enableAutoFocus)
+            {
+                StartCoroutine(AutoFocusCoroutine());
+            }
         }
      
 
@@ -264,6 +285,29 @@ namespace Kill.UI.Pages
             previewTexture.Apply();
         }
 
+        /// <summary>
+        /// 自动对焦维护协程
+        /// iOS: 走原生插件（连续自动对焦已启用，只需定期触发即可）
+        /// 其他平台: 使用 WebCamTexture.autoFocusPoint 定期设置对焦点
+        /// </summary>
+        private IEnumerator AutoFocusCoroutine()
+        {
+            while (isScanning)
+            {
+#if UNITY_IOS && !UNITY_EDITOR
+                // iOS 通过原生插件触发一次自动对焦
+                _TriggerAutoFocus();
+#else
+                // Android/其他: 定期重置对焦点到画面中心
+                if (webCamTexture != null && webCamTexture.isPlaying)
+                {
+                    webCamTexture.autoFocusPoint = new Vector2(0.5f, 0.5f);
+                }
+#endif
+                yield return new WaitForSeconds(focusInterval);
+            }
+        }
+
         [SerializeField] private float previewUpdateInterval = 0.03f; // 预览更新间隔（20fps）
         
         /// <summary>