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我以為還要去找第三方套件來用，一查網路才發現，從iOS 7開始，SDK已經內建有掃描條碼的API，我想會把這功能納入麾下是必然的，因為在生活中條碼無所不在，除了常見的用途如辨識商品（書籍、食品、識別證等）外，還能做非常有趣的應用（導覽、遊戲等）。

猜猜看可以掃到什麼？

現在就來學一下怎麼掃描QR Code和Bar Code吧！

掃描條碼的API被收錄在AVFoundation Framework，目前可支援以下規格條碼：

• UPC-A
• UPC-E
• Code 39
• Code 39 mod 43
• Code 93
• Code 128
• EAN-8
• EAN-13
• Aztec
• PDF417
• QR

我們直接來寫程式吧～

/**
 Theme: Scan QR Code & Bar Code
 IDE: Xcode 7
 Language: Objective C
 Date: 104/11/19
 Author: HappyMan
 Blog: https://cg2010studio.wordpress.com/
 */
#import <AVFoundation/AVFoundation.h>

@interface TRCRecordRegisterViewController : UIViewController <AVCaptureMetadataOutputObjectsDelegate>
{
 IBOutlet UILabel *statementLabel;
 IBOutlet UIView *scanView;
}

@property (nonatomic, strong) AVCaptureSession *captureSession;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
@property (nonatomic) BOOL isReading;

-(BOOL)startReading;
-(void)stopReading;

@end

@implementation TRCRecordRegisterViewController
#pragma mark - IBAction method implementation
- (void)viewDidLoad {
    [super viewDidLoad];

    // Initially make the captureSession object nil.
    _captureSession = nil;
    
    // Set the initial value of the flag to NO.
    _isReading = NO;
    
    [self startStopReading:nil];
}

- (IBAction)startStopReading:(id)sender {
    if (!_isReading) {
        // This is the case where the app should read a QR code when the start button is tapped.
        if ([self startReading]) {
            // If the startReading methods returns YES and the capture session is successfully
            // running, then change the start button title and the status message.
        }
    }
    else{
        // In this case the app is currently reading a QR code and it should stop doing so.
        [self stopReading];
        // The bar button item's title should change again.
    }
    
    // Set to the flag the exact opposite value of the one that currently has.
    _isReading = !_isReading;
}

#pragma mark - Private method implementation

- (BOOL)startReading {
    NSError *error;
    
    // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video
    // as the media type parameter.
    AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    // Get an instance of the AVCaptureDeviceInput class using the previous device object.
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&amp;amp;error];
    
    if (!input) {
        // If any error occurs, simply log the description of it and don't continue any more.
        NSLog(@"%@", [error localizedDescription]);
        return NO;
    }
    
    // Initialize the captureSession object.
    _captureSession = [[AVCaptureSession alloc] init];
    // Set the input device on the capture session.
    [_captureSession addInput:input];
    
    // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
    AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    [_captureSession addOutput:captureMetadataOutput];
    
    // Create a new serial dispatch queue.
    dispatch_queue_t dispatchQueue;
    dispatchQueue = dispatch_queue_create("myQueue", NULL);
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
    [captureMetadataOutput setMetadataObjectTypes:[captureMetadataOutput availableMetadataObjectTypes]];

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
    [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [_videoPreviewLayer setFrame:scanView.layer.bounds];
    [scanView.layer addSublayer:_videoPreviewLayer];
    
    
    // Start video capture.
    [_captureSession startRunning];
    
    return YES;
}

-(void)stopReading{
    // Stop video capture and make the capture session object nil.
    [_captureSession stopRunning];
    _captureSession = nil;
    
    // Remove the video preview layer from the viewPreview view's layer.
    [_videoPreviewLayer removeFromSuperlayer];
}

#pragma mark - AVCaptureMetadataOutputObjectsDelegate method implementation

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    
    // Check if the metadataObjects array is not nil and it contains at least one object.
    if (metadataObjects != nil &amp;amp;&amp;amp; [metadataObjects count] &amp;gt; 0) {
        
        NSLog(@"Result:%@", metadataObjects);
        // Get the metadata object.
        AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
        if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeCode93Code] || [[metadataObj type] isEqualToString:AVMetadataObjectTypeCode128Code]) {
            // If the found metadata is equal to the QR code metadata then update the status label's text,
            // stop reading and change the bar button item's title and the flag's value.
            // Everything is done on the main thread.
            // 掃瞄完畢停止重複掃描
            [self stopReading];

            [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];
            
            _isReading = NO;
        }
    }   
}

@end

以上程式碼需配合IB來實現，呈現的介面如下～

我在程式中設定可以掃所有支援的條碼：

• [captureMetadataOutput availableMetadataObjectTypes]

而在掃瞄到的條碼只對以下兩種做處理：

• AVMetadataObjectTypeCode93Code
• AVMetadataObjectTypeCode128Code

如果想要處理QR Code，可以使用：

• AVMetadataObjectTypeQRCode

實際操作如首圖以及下圖：

這是我購物時會請店員幫我掃瞄載具手機條碼，方便我記帳和對獎囉～

掃到後會得到分別如下的資訊：

Result:(

“<AVMetadataMachineReadableCodeObject: 0x15055e4c0, type=\"org.iso.QRCode\", bounds={ 0.4,0.5 0.2×0.3 }>corners { 0.4,0.8 0.5,0.9 0.5,0.6 0.4,0.5 }, time 126077075932541, stringValue \"https://cg2010studio.wordpress.com\""

)

Result:(

“<AVMetadataMachineReadableCodeObject: 0x14ed975e0, type=\"org.iso.Code39\", bounds={ 0.2,0.4 0.4×0.1 }>corners { 0.6,0.5 0.6,0.5 0.2,0.4 0.2,0.4 }, time 126242691839958, stringValue \"/OIZHBKQ\""

)

可以試試看掃不是條碼的東西，可能會有很奇妙的發現喔：Ｐ～

最近在提攜公司新人，跟他說明很多功能可以找現成的來套，如此能省下非常多的時間，以便把火力集中在核心功能上！什麼是核心功能呢？要是我能做自家的產品，就自己來研發一套演算法流程吧！

參考：How To Scan QR Code Using AVFoundation Framework、Scanning Barcodes with iOS 7 (Objective-C)。