Swift委托和SocketScan scanApi.setDelegate（）

iOS的SocketScan API是用Objective-C编写的，旨在将CHS模式下的SocketMobile扫描仪集成到本机应用程序中

启动ScanApi时，需要将ViewController设置为ScanApiHelperDelegate，这需要在viewDidLoad上进行一些设置，以及从扫描仪接收操作的一些函数

变量设置为：

var scanApi = ScanApiHelper()
var scanApiConsumer = NSTimer()

然后在viewDidLoad中，实现以下代码：

scanApi.setDelegate(self)
scanApi.open()
scanApiConsumer = NSTimer.scheduledTimerWithTimeInterval(0.2, target: self, selector:Selector("onTimer"), userInfo: nil, repeats: true)

然后，scanApiConsumer调用以下函数以侦听来自扫描仪的通知：

func onTimer () -> Void{
    scanApi.doScanApiReceive()
    scanApi.getDevicesList()
}

扫描条形码时，它执行以下操作：

func onDecodedData(device: DeviceInfo, decodedData: ISktScanDecodedData) {
    //code to execute here
}

如果需要，用户将被路由到另一个视图，在该视图中扫描条形码会执行不同的代码。scanApi.setDelegate的设置如下：

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "manifestToRepackContainer" {
        let vc = (segue.destinationViewController as RepackContainer)
        scanApi.setDelegate(vc)
        vc.containerBarcode = GlobalVars.barcodeData
    }
}

这也很有效。到达后，扫描仪将正确执行指定的功能。而且，在ViewDid出现在原始查看器上时，我有此设置，它也可以按预期工作：

override func viewDidAppear(animated: Bool) {
    scanApi.setDelegate(self)
}

当用户需要在情节提要的一个完全不同的区域（“远程”视图）中扫描功能时，就会出现问题，其中prepareForSegue方法无法触发scanApi.setDelegate（）

我最初的想法是，通过在“远程”视图中执行scanApi.setDelegate（self），在“远程”视图中定义scanApi委托。当然，此视图也被指定为scanApiHelperDelegate，并包含所有需要的函数。但是，它不起作用。原始viewController仍然是代理，扫描条形码将继续触发原始viewController中列出的功能，而不是当前功能。编译器不返回任何错误

我怀疑可能是a）与Swift与Objective-C API交互的方式有关，或者b）我使用“self”错误地声明了什么应该是新的scanApi委托

---

那么，在这种情况下，声明新的scanApi委托的正确方法是什么？这是API的问题吗？

当前版本的scanApi Helper不支持多个委托视图，但未来版本将支持多个委托视图。如果您想将其添加到项目中的ScanApiHelper，以下是我们所做的修改

注意：这些更改是向后兼容的，因此即使您不需要支持多个代理视图，也可以在ScanApiHelper发布时安全地应用这些更改或升级到最新版本

ScanApiHelper.h

Index: ScanApiHelper.h
===================================================================
--- ScanApiHelper.h (revision 12778)
+++ ScanApiHelper.h (revision 12779)
@@ -65,6 +65,7 @@
 @end

 @protocol ScanApiHelperDelegate <NSObject>
+@optional
 /**
  * called each time a device connects to the host
  * @param result contains the result of the connection
@@ -103,7 +104,6 @@
  */
 -(void) onErrorRetrievingScanObject:(SKTRESULT) result;

-@optional
 /**
  * called each time ScanAPI receives decoded data from scanner
  * @param result is ESKT_NOERROR when decodedData contains actual
@@ -179,9 +179,15 @@
     id<ISktScanApi>_scanApi;
     id<ISktScanObject>_scanObjectReceived;
     NSObject* _commandContextsLock;
+    BOOL _shared;// to indicate when ScanApiHelper is shared across multiple views
+    NSMutableArray* _delegateStack;
 }

++(ScanApiHelper*)sharedScanApiHelper;

+-(void)pushDelegate:(id<ScanApiHelperDelegate>)delegate;
+-(void)popDelegate:(id<ScanApiHelperDelegate>)delegate;
+
 /**
  * register for notifications in order to receive notifications such as
  * "Device Arrival", "Device Removal", "Decoded Data"...etc...

索引：ScanApiHelper.h
===================================================================
---ScanApiHelper.h（12778版）
+++ScanApiHelper.h（12779版）
@@ -65,6 +65,7 @@
@结束
@协议ScanApiHelperDelegate
+@可选的
/**
*每次设备连接到主机时调用
*@param result包含连接的结果
@@ -103,7 +104,6 @@
*/
-（void）onErrorRetrievingScanObject:（SKTRESULT）结果；
-@可选的
/**
*每次ScanAPI从扫描仪接收解码数据时调用
*当decodedData包含实际值时，@param结果为ESKT_NOERROR
@@ -179,9 +179,15 @@
id_scanApi；
已收到的身份证；
NSObject*_commandContextsLock；
+BOOL_shared；//指示何时跨多个视图共享ScanApiHelper的步骤
+NSMutableArray*_delegateStack；
}
++（ScanApiHelper*）共享的ScanApiHelper；
+-（无效）代理：（id）代理；
+-（void）popDelegate:（id）delegate；
+
/**
*注册通知以接收通知，例如
*“设备到达”、“设备移除”、“解码数据”等。。。

ScanApiHelper.mm

Index: ScanApiHelper.mm
===================================================================
--- ScanApiHelper.mm    (revision 12778)
+++ ScanApiHelper.mm    (revision 12779)
@@ -105,12 +105,16 @@
 @implementation ScanApiHelper

 -(id)init{
+    static ScanApiHelper* sharedScanApiHelper=nil;
     self=[super init];
     if(self!=nil){
+        sharedScanApiHelper=self;
         _commandContextsLock=[[NSObject alloc]init];
         _deviceInfoList=[[NSMutableDictionary alloc]init];
         _scanApiOpen=FALSE;
         _scanApiTerminated=TRUE;// by default ScanApi is not started
+        _shared=NO;
+        _delegateStack=[[NSMutableArray alloc]init];
     }
     return self;
 }
@@ -130,6 +134,7 @@
     _commandContextsLock=nil;

     _deviceInfoList=nil;
+    _delegateStack=nil;
 }
 #else
 -(void)dealloc{
@@ -151,10 +156,54 @@

     [_deviceInfoList release];
     _deviceInfoList=nil;
+    
+    [_delegateStack release];
+    _delegateStack=nil;
+    
     [super dealloc];
 }
 #endif

++(ScanApiHelper*)sharedScanApiHelper{
+    static ScanApiHelper* scanApiHelper=nil;
+    if(scanApiHelper==nil){
+        scanApiHelper=[[ScanApiHelper alloc]init];
+        scanApiHelper->_shared=YES;
+    }
+    return scanApiHelper;
+}
+
+-(void)pushDelegate:(id<ScanApiHelperDelegate>)delegate{
+    if(_delegate != delegate){
+        if(_delegate!=nil){
+            [_delegateStack addObject:_delegate];
+        }
+        _delegate=delegate;
+        [self generateDeviceArrivals];
+    }
+}
+
+-(void)popDelegate:(id<ScanApiHelperDelegate>)delegate{
+    if(_delegate ==delegate){
+        if(_delegateStack.count>0){
+            id<ScanApiHelperDelegate> newDelegate=[_delegateStack objectAtIndex:_delegateStack.count-1];
+            [_delegateStack removeLastObject];
+            _delegate = newDelegate;
+            // generate a device Arrival for each scanner we've already receive
+            // so that the new view can be aware of the connected scanners
+            if(_delegate!=nil){
+                for (NSString* key in _deviceInfoList) {
+                    DeviceInfo* device=[_deviceInfoList objectForKey:key];
+                    [_delegate onDeviceArrival:ESKT_NOERROR device:device];
+                }
+            }
+        }
+        else{
+            _delegate=nil;
+        }
+    }
+}
+
 /**
  * register for notifications in order to receive notifications such as
  * "Device Arrival", "Device Removal", "Decoded Data"...etc...
@@ -1519,14 +1568,15 @@
 #endif    
     // release the previous ScanAPI object instance if
     // it exists
-    if(_scanApi!=nil){
-        [_scanApi close];
-        [SktClassFactory releaseScanApiInstance:_scanApi];
-    }
     _scanApi=[SktClassFactory createScanApiInstance];
     SKTRESULT result=[_scanApi open:nil];
-    if(_delegate!=nil)
-        [_delegate onScanApiInitializeComplete:result];
+    if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onScanApiInitializeComplete:)])){
+        [_delegate onScanApiInitializeComplete:result];
+    }
     _scanApiTerminated=FALSE;

 #if __has_feature(objc_arc)
@@ -1576,8 +1626,9 @@
             }
         }
         else{
-            if(_delegate!=nil)
+            if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onErrorRetrievingScanObject:)])){
                 [_delegate onErrorRetrievingScanObject:result];
+            }
         }
     }
     return result;
@@ -1600,8 +1651,9 @@
             result=[self handleDeviceRemoval:scanObj];
             break;
         case kSktScanMsgIdTerminate:
-            if(_delegate!=nil)
+            if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onScanApiTerminated)])){
                 [_delegate onScanApiTerminated];
+            }
             closeScanApi=TRUE;
             break;
         case kSktScanMsgSetComplete:
@@ -1619,8 +1671,9 @@

     // if there is an error then report it to the ScanAPIHelper user
     if(!SKTSUCCESS(result)){
-        if(_delegate!=nil)
+        if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onError:)])){
             [_delegate onError:result];
+        }
     }
     return closeScanApi;
 }
@@ -1657,8 +1710,9 @@
     }

     // notify the ScanApiHelper user a scanner has connected to this host
-    if(_delegate!=nil)
+    if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onDeviceArrival:device:)])){
         [_delegate onDeviceArrival:result device:deviceInfo];
+    }

 #if __has_feature(objc_arc)
 #else 
@@ -1702,8 +1756,9 @@
     [SktClassFactory releaseDeviceInstance:scanDevice];

     // notify the ScanApiHelper user a scanner has connected to this host
-    if(_delegate!=nil)
+    if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onDeviceRemoval:)])){
         [_delegate onDeviceRemoval:deviceInfo];
+    }

     return result;
 }
@@ -1766,7 +1821,7 @@
             result=[self handleDecodedData:scanObj];
             break;
         case kSktScanEventError:
-            if(_delegate!=nil)
+            if((_delegate!=nil)&&([_delegate respondsToSelector:@selector(onError:)]))
                 [_delegate onError:[[scanObj Msg]Result]];
             break;

@@ -1809,6 +1864,7 @@
     return result;
 }

 /**
  * sendNextCommand
  *
@@ -1855,4 +1911,25 @@
     return result;
 }

+/**
+ *  generateDeviceArrivals
+ *
+ *  internal function to generate device
+ *  arrival notifications when the delegate
+ *  change to a new delegate.
+ *  This is used in a multi views application
+ *  that has more than one view to receive the
+ *  decoded data
+ */
+-(void)generateDeviceArrivals{
+    // generate a device Arrival for each scanner we've already receive
+    // so that the new view can be aware of the connected scanners
+    if(_delegate!=nil){
+        for (NSString* key in _deviceInfoList) {
+            DeviceInfo* device=[_deviceInfoList objectForKey:key];
+            [_delegate onDeviceArrival:ESKT_NOERROR device:device];
+        }
+    }
+}
+
 @end

索引：ScanApiHelper.mm
===================================================================
---ScanApiHelper.mm（版本12778）
+++ScanApiHelper.mm（版本12779）
@@ -105,12 +105,16 @@
@ScanApiHelper的实现
-（id）init{
+静态ScanApiHelper*sharedScanApiHelper=nil；
self=[super init]；
if（self！=nil）{
+sharedScanApiHelper=self；
_commandContextsLock=[[NSObject alloc]init]；
_DeviceInfo列表=[[NSMutableDictionary alloc]init]；
_scanApiOpen=FALSE；
_scanApiTerminated=TRUE；//默认情况下，未启动ScanApi
+_shared=否；
+_delegateStack=[[NSMutableArray alloc]init]；
}
回归自我；
}
@@ -130,6 +134,7 @@
_commandContextsLock=nil；
_DeviceInfo列表=零；
+_delegateStack=nil；
}
#否则
-（无效）解除锁定{
@@ -151,10 +156,54 @@
[_设备信息列表发布]；
_DeviceInfo列表=零；
+    
+[_delegatestackrelease]；
+_delegateStack=nil；
+    
[super dealoc]；
}
#恩迪夫
++（ScanApiHelper*）共享的ScanApiHelper{
+静态ScanApiHelper*ScanApiHelper=nil；
+if（scanApiHelper==nil）{
+scanApiHelper=[[scanApiHelper alloc]init]；
+scanApiHelper->_shared=YES；
+    }
+返回帮助者；
+}
+
+-（无效）pushDelegate:（id）delegate{
+如果（_delegate！=委托）{
+如果（_delegate！=nil）{
+[_delegatestackaddobject:_delegate]；
+        }
+_delegate=代表；
+[自生副产品]；
+    }
+}
+
+-（void）popDelegate:（id）delegate{
+如果（_delegate==委托）{
+如果（_delegateStack.count>0）{
+id newDelegate=[\u delegateStack objectAtIndex:\u delegateStack.count-1]；
+[_delegatestackremovelastobject]；
+_delegate=newDelegate；
+//为我们已经收到的每个扫描仪生成设备到达
+//以便新视图能够识别已连接的扫描仪
+如果（_delegate！=nil）{
+用于（NSString*输入设备信息列表）{
+DeviceInfo*设备=[\u DeviceInfo列表对象forkey:key]；
+[_delegateondevicearrival:ESKT_NOERROR device:device]；
+                }
+            }
+        }
+否则{
+_delegate=nil；
+        }
+    }
+}
+
/**
*注册通知以接收通知，例如
*“设备到达”、“设备移除”