适用于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功能。
Vars已设置：
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调用以下函数来侦听来自扫描程序的通知：
func onTimer () -> Void{
scanApi.doScanApiReceive()
scanApi.getDevicesList()
}
扫描条形码时，会执行以下操作：
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，其中扫描条形码执行不同的代码。 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。一旦你在那里，扫描仪正确执行指定的功能。而且，在原始查看器的viewDidAppear上，我有这个设置，它也按预期工作：
override func viewDidAppear(animated: Bool) {
scanApi.setDelegate(self)
}
当用户需要在故事板的完全不同的区域（“远程”视图）中扫描功能时会出现问题，其中prepareForSegue方法无法触发scanApi.setDelegate（）
我最初的想法是通过在“远程”视图的viewDidAppear中执行scanApi.setDelegate（self）来简单地在“远程”视图中定义scanApi委托。当然，此视图也被指定为scanApiHelperDelegate并包含所有需要的功能。但是，它不起作用。原始的viewController仍然是委托，扫描条形码继续触发原始viewController中列出的功能，而不是当前的。编译器不会返回任何错误。
我怀疑它是a）关于Swift与Objective-C API交互的方式或b）我错误地通过使用“self”声明新的scanApi委托应该是什么。
那么，在这种情况下声明新的scanApi委托的正确方法是什么，或者这是API的问题？
答案 0 :(得分：1)
当前版本的ScanApiHelper不支持多个委托视图，但未来版本将支持。如果您要将其添加到项目中的ScanApiHelper，我们将进行修改。
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，您也可以安全地应用这些更改或升级到最新版本的ScanApiHelper
<强> 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...
<强> 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