Generation and use of QR codes in iOS (introductory article)

Here is a brief summary of the two-dimensional code scanning and generation, with the original avfoundation framework, in fact, the framework is still adequate for the current function, but here is recommended a two-dimensional code scanning of the third party (face++), the URL is not affixed, the direct degree Niang OK, the contents of the content is rich enough, Interested friends can go to dealing things for themselves.

A. Two-dimensional code scanning

Steps: 1. Create an Input video device (default is a rear camera) 2. Create an input Device Object 3. Create a meta-data output device 4. Create a session to link inputs and outputs 5. Add the output device to the session, Add the input device to the SESSION6. Set the type of the data source (requires a real machine to have a value), specify the agent (listener results in Proxy method) 7. Start scanning 8. Add a video preview interface (here is the open Camera 9. Implementation code implementation of the Proxy method:

1- (void) Viewdidload {2 [Super Viewdidload];3 4 //1. Create an input video device5     //The default is the rear-facing camera6Avcapturedevice * device =[Avcapturedevice Defaultdevicewithmediatype:avmediatypevideo];7 //2. Create an input device object8Nserror * ERROR =Nil;9Avcapturedeviceinput * InputDevice = [[Avcapturedeviceinput alloc]initwithdevice:device error:&ERROR];Ten      One //3. Create a meta-data output device AAvcapturemetadataoutput * Outputdevice =[[Avcapturemetadataoutput alloc]init]; - //4. Create a session (function to connect inputs and outputs) -Self.session =[[Avcapturesession alloc]init]; the //5. Add the output device to the session -     if([self.session Canaddoutput:outputdevice]) { - [Self.session Addoutput:outputdevice]; -     } + //6. Add a session to the input device -     if([self.session Canaddinput:inputdevice]) { + [Self.session Addinput:inputdevice]; A     } at //7. Set the data source type, this value will have the value of the real machine - //NSLog (@ "%@", outputdevice.availablemetadataobjecttypes); -Outputdevice.metadataobjecttypes = @[@"Org.iso.QRCode"]; -     //set the proxy for the output - [Outputdevice setmetadataobjectsdelegate:self queue:dispatch_get_main_queue ()]; - //8. Start Scanning in [Self.session startrunning]; -      to //9. Setting up the preview screen +     //Video preview Layer -Avcapturevideopreviewlayer * PREVIEWL =[[Avcapturevideopreviewlayer alloc]initwithsession:self.session]; the     //Set Frame *Previewl.frame =self.view.bounds; $     //add to view of controllerPanax Notoginseng [Self.view.layer ADDSUBLAYER:PREVIEWL]; -      the } +  A #pragmaMark-avcapturemetadataoutputobjectsdelegate the //The result of printing output in this agent +- (void) Captureoutput: (Avcaptureoutput *) captureoutput didoutputmetadataobjects: (Nsarray *) metadataobjects fromConnection :(Avcaptureconnection *) Connection - { $Avmetadatamachinereadablecodeobject *Object=[Metadataobjects Firstobject]; $NSLog (@"%@",Object. stringvalue); -     //Stop the scan so the camera will stop. - [Self.session stoprunning]; the}

Two. Generation of two-dimensional code (this column is a picture of a two-dimensional code generated from a piece of text)

1  1.1Create a filter to generate two-dimensional code2Cifilter *qrfilter = [Cifilter filterwithname:@"Ciqrcodegenerator"];3NSData *messagedata = [@"How are you doing recently? "datausingencoding:nsutf8stringencoding];4 //1.2 Setting the input of a two-dimensional filter5[Qrfilter setvalue:messagedata Forkey:@"InputMessage"];6 //1.3 Take out the picture7Ciimage *ciimage =Qrfilter.outputimage;8 //1.4 Enlarge Image9Ciimage = [Ciimage Imagebyapplyingtransform:cgaffinetransformmakescale (8,8)];Ten          One #pragmaMark-Modify the foreground and background colors of the QR code A //Modify the foreground and background colors of the QR code, and when you modify the foreground or background color, it will decrease the image's recognition level . -Cifilter *falsecolorfilter = [Cifilter filterwithname:@"Cifalsecolor"]; - //inputimage, Photo the //inputColor0, foreground color - //InputColor1 Background Color - //These three parameters are all objects in the Coreimage - //NSLog (@ "%@", Falsecolorfilter.inputkeys); + //Image -[Falsecolorfilter setvalue:ciimage Forkey:@"Inputimage"]; + //Front View A[Falsecolorfilter setvalue:[cicolor colorwithred:1Green0Blue0] Forkey:@"InputColor0"]; at //Background Color -[Falsecolorfilter setvalue:[cicolor colorwithred:0Green0Blue1] Forkey:@"InputColor1"]; -     -      -  - //Remove the picture from the filter inCiimage =Falsecolorfilter.outputimage; -      to //Two-dimensional code above the addition of avatars, will also reduce the recognition of two-dimensional code +UIImage *qrimage =[UIImage imagewithciimage:ciimage]; -      the #pragmaMark-Draw a picture of the original QR code * //draw a picture of the original QR code $ //Open Picture ContextPanax Notoginseng Uigraphicsbeginimagecontext (qrimage.size); - //drawing two-dimensional code images the[Qrimage Drawinrect:cgrectmake (0,0, QrImage.size.width, QrImage.size.height)]; + //Drawing an avatar AUIImage *headimage = [UIImage imagenamed:@"Cang"]; theCGFloat HEADW = QrImage.size.width *0.2; +CGFloat headh = QrImage.size.height *0.2; -CGFloat HEADX = (QRIMAGE.SIZE.WIDTH-HEADW) *0.5; $CGFloat heady = (qrimage.size.height-headh) *0.5; $ [Headimage drawinrect:cgrectmake (HEADX, Heady, HEADW, headh)]; - //remove a picture from the picture context -Qrimage =Uigraphicsgetimagefromcurrentimagecontext (); the      - //Close Picture ContextWuyi Uigraphicsendimagecontext (); the      - //1.6 Convert Ciimage to UIImage WuSelf.imageView.image =Qrimage; -     

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PS: This column is relatively simple, write relatively humble, follow-up demand will gradually improve, we have what good code can also be affixed to the exchange.

Generation and use of QR codes in iOS (introductory article)