我正在尝试使用 Apple 原生 API 扫描 Aztec 代码。但我无法扫描它。 Apple guideline里面，我看过了，可以扫描Aztec code。但它不起作用。

请检查我使用的代码。

#import <UIKit/UIKit.h>

@interface igViewController : UIViewController

@end

#import <AVFoundation/AVFoundation.h>
#import "igViewController.h"

@interface igViewController () <AVCaptureMetadataOutputObjectsDelegate>
{
    AVCaptureSession *_session;
    AVCaptureDevice *_device;
    AVCaptureDeviceInput *_input;
    AVCaptureMetadataOutput *_output;
    AVCaptureVideoPreviewLayer *_prevLayer;

    UIView *_highlightView;
    UILabel *_label;
}
@end

@implementation igViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    _highlightView = [[UIView alloc] init];
    _highlightView.autoresizingMask = UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleBottomMargin;
    _highlightView.layer.borderColor = [UIColor greenColor].CGColor;
    _highlightView.layer.borderWidth = 3;
    [self.view addSubview:_highlightView];

    _label = [[UILabel alloc] init];
    _label.frame = CGRectMake(0, self.view.bounds.size.height - 40, self.view.bounds.size.width, 40);
    _label.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
    _label.backgroundColor = [UIColor colorWithWhite:0.15 alpha:0.65];
    _label.textColor = [UIColor whiteColor];
    _label.textAlignment = NSTextAlignmentCenter;
    _label.text = @"(none)";
    [self.view addSubview:_label];

    _session = [[AVCaptureSession alloc] init];
    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    NSError *error = nil;

    _input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:&error];
    if (_input) {
        [_session addInput:_input];
    } else {
        NSLog(@"Error: %@", error);
    }

    _output = [[AVCaptureMetadataOutput alloc] init];
    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [_session addOutput:_output];

    _output.metadataObjectTypes = [_output availableMetadataObjectTypes];
for (NSString* avail in _output.metadataObjectTypes) {
  NSLog(@"Avail...%@", avail);
          }
    _prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    _prevLayer.frame = self.view.bounds;
    _prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:_prevLayer];

    [_session startRunning];

    [self.view bringSubviewToFront:_highlightView];
    [self.view bringSubviewToFront:_label];
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
NSLog(@"Failed...");
    CGRect highlightViewRect = CGRectZero;
    AVMetadataMachineReadableCodeObject *barCodeObject;
    NSString *detectionString = nil;
    NSArray *barCodeTypes = @[AVMetadataObjectTypeAztecCode];

    for (AVMetadataObject *metadata in metadataObjects) {
                    NSLog(@".....%@", metadata.type);
        for (NSString *type in barCodeTypes) {
            if ([metadata.type isEqualToString:type])
            {
                barCodeObject = (AVMetadataMachineReadableCodeObject *)[_prevLayer transformedMetadataObjectForMetadataObjectAVMetadataMachineReadableCodeObject *)metadata];
                highlightViewRect = barCodeObject.bounds;
                detectionString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
                break;
            }
        }

        if (detectionString != nil)
        {
            _label.text = detectionString;
            break;
        }
        else
            _label.text = @"(none)";
    }

//_label.text = @"(nonessss)";

    _highlightView.frame = highlightViewRect;
}

@end

最佳答案

这是我对 SO 的第一个回答，我是 Objective-C 和 iOS 开发的初学者，所以请对我温和一点。

我实际上无法帮助您修复代码中的错误，因为作为初学者，我仍然很难看到发生了什么，但我想告诉您，就在几天前，我成功地关注了 this tutorial如何准确地做你需要的。我调整了教程代码并在需要的地方添加了注释，因此如果您想尝试，应该很容易理解。似乎只在这里发布链接是不受欢迎的，所以我发布了我的代码。

这是一个 ViewController，它直接打开扫描 View 并在找到条形码(在我的例子中是 aztec)时使用react。它应该很容易适应您的需要。在教程中，他们使用了 AVMetadataObjectTypeQRCode，但要扫描 Aztec 代码，只需将其替换为 AVMetadataObjectTypeAztecCode。我已经在我的代码中这样做了。

ScanVC.h(在您的例子中是 igViewController)

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface ScanVC : UIViewController <AVCaptureMetadataOutputObjectsDelegate>

@property (retain, nonatomic) UILabel *scannerWindow;
@property (retain, nonatomic) UILabel *statusLabel;
@property (retain, nonatomic) UIButton *cancelButton;

@end

ScanVC.m

#import "ScanVC.h"

@interface ScanVC ()

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

@end


@implementation ScanVC

@synthesize cancelButton;
@synthesize statusLabel;
@synthesize scannerWindow;


- (void)viewDidLoad {
    [super viewDidLoad];

    _isReading = NO;
    _captureSession = nil;

    //place a close button
    cancelButton = [UIButton buttonWithType:UIButtonTypeSystem];
    [cancelButton addTarget:self action:@selector(closeScan) forControlEvents:UIControlEventTouchUpInside];
    [cancelButton setTitle:@"Close" forState:UIControlStateNormal];
    cancelButton.frame = CGRectMake(0, 410, 250, 40);
    [self.view addSubview:cancelButton];

    //place a status label
    statusLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 340, 250, 40)];
    statusLabel.text = @"Currently not scanning";
    [self.view addSubview:statusLabel];

    //place the scanner window (adjust the size)
    scannerWindow = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 250, 250)];
    scannerWindow.text = @"Camera Capture Window";
    [self.view addSubview:scannerWindow];

    //start the scan immediately when the view loads
    [self startStopScan];
}

- (void)closeScan {
    if(_isReading) {
        [self stopReading];
    }

    _isReading = !_isReading;

    //dismiss the view controller here?
    }];
}

- (void)startStopScan {

    if (!_isReading) {
        if([self startReading]) {
            [statusLabel setText:@"Scanning for Barcode"];
        }
    } else {
        [self stopReading];
    }

    _isReading = !_isReading;
}

- (BOOL)startReading {
    NSError *error;

    AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

    if(!input) {
        NSLog(@"%@", [error localizedDescription]);
        return NO;
    }

    _captureSession = [[AVCaptureSession alloc] init];
    [_captureSession addInput:input];

    AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    [_captureSession addOutput:captureMetadataOutput];

    dispatch_queue_t dispatchQueue;
    dispatchQueue = dispatch_queue_create("myQueue", NULL);
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
    [captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeAztecCode]];

    //show the preview to the user
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
    [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [_videoPreviewLayer setFrame:scannerWindow.layer.bounds];
    [scannerWindow.layer addSublayer:_videoPreviewLayer];

    [_captureSession startRunning];

    return YES;
}

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    if (metadataObjects != nil && [metadataObjects count] > 0) {
        AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
        if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeAztecCode]) {
            [statusLabel performSelectorOnMainThread:@selector(setText:) withObject:[metadataObj stringValue] waitUntilDone:NO];

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



            //do things after a successful scan here
            NSLog(@"scanner output %@", [metadataObj stringValue]);
        }
    }
}

- (void)stopReading {
    [_captureSession stopRunning];
    _captureSession = nil;

    [_videoPreviewLayer removeFromSuperlayer];
}


@end

关于ios - Aztec 代码未扫描，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23219885/