IOS system QR Code scan (can limit scan area)

Source: Internet
Author: User

Use the Avfoundation system library to scan the QR code and limit the scope of the QR code. (Because the default is full screen scanning)

-(void) Begincode

{

1. Camera Device

Avcapturedevice *device = [Avcapturedevice defaultdevicewithmediatype:avmediatypevideo];

/*

Media types

Avmediatypevideo

Avmediatypeaudio

Avmediatypetext

Avmediatypeclosedcaption

Avmediatypesubtitle

Avmediatypetimecode

Avmediatypemetadata

Avmediatypemuxed

*/

2. Setting the input

/**

* Set input This method needs to be judged because the simulator does not have a webcam

*

* @param the camera as the input device

*

* @return return Avcaptureinput

*/

Nserror *error = nil;

Avcaptureinput *input = [Avcapturedeviceinput deviceinputwithdevice:device error:&error];

if (Error) {

NSLog (@ "No webcam%@", error);

Return

}

3. Set output (Metdata metadata)

Avcapturemetadataoutput *output = [[Avcapturemetadataoutput alloc] init];

3.1 Output of the proxy captures the image of the two-dimensional code

Dispatch_get_main_queue () uses the main thread queue, responds to comparison synchronization, and responds differently with other queues.

[Output Setmetadataobjectsdelegate:self queue:dispatch_get_main_queue ()];

3.2 Setting scan area By default is full screen scan

This cgrectmake (y,x,h,w) 1 means that the maximum origin is the start point in the lower right corner of the navigation

[Output setrectofinterest:cgrectmake (0, 0.5, 0.5, 0.5)];//upper left corner 1/4 screen

[Output Setrectofinterest:cgrectmake (0.5, 0.5, 0.5, 0.5)];//lower left corner 1/4 screen

[Output Setrectofinterest:cgrectmake (0.5, 0, 0.5, 0.5)]; Lower right corner 1/4 screen

[Output setrectofinterest:cgrectmake (0, 0, 0.5, 0.5)]; Top Right corner 1/4 screen

[Output Setrectofinterest:cgrectmake (124)/screenhigh, ((ScreenWidth220)/2)/screenwidth,220/screenhigh,220 /screenwidth)]; Set the location of a custom pixel point

[Output Setrectofinterest:cgrectmake (0.25,0.25, 0.5, 0.5)]; Looks like the middle of the feeling!!!

4. Shooting Sessions

Avcapturesession *session = [[Avcapturesession alloc] init];

_session = session;

Add input and output to session

[Session Addinput:input];

[Session Addoutput:output];

4.1 Setting the format of the output

[Output SETMETADATAOBJECTTYPES:@[AVMETADATAOBJECTTYPEQRCODE]];

5. Set the preview layer (let the user see the scan results)

Avcapturevideopreviewlayer *preview = [Avcapturevideopreviewlayer layerwithsession:session];

_previewlayer = preview;

5.1 Setting the properties of the preview

preview.videogravity = Avlayervideogravityresizeaspectfill;

5.2 Setting the size of the preview layer

[Preview SetFrame:self.view.bounds];

5.3 Adding layers to a view's layer

[Self.view.layer Insertsublayer:preview atindex:0];

6. Start the session

[Session startrunning];

}

Proxy method for #pragma mark output

This method is recognized in the QRCode, and the conversion is completed

If the content of the QRCode is larger, the longer the conversion takes

-(void) Captureoutput: (Avcaptureoutput *) captureoutput didoutputmetadataobjects: (Nsarray *) metadataobjects Fromconnection: (avcaptureconnection *) connection

{

Will scan frequently.

Stop if the scan is complete

[_session stoprunning];

Delete a previewed layer

[_previewlayer Removefromsuperlayer];

Set interface to display scan results

NSString *reslutstr = [[NSString alloc] init];

if (Metadataobjects.count > 0) {

Avmetadatamachinereadablecodeobject *obj = metadataobjects[0];

Reslutstr = [obj stringvalue]; //This is the result of the scan

If you need to scan for information such as a URL card to expand again

}

NSLog (@ "%@", metadataobjects);

}

IOS system QR Code scan (can limit scan area)

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