我正在尝试加快我的应用程序中条形码的读取速度，该应用程序可以正常工作，但在读取条形码时有点慢。
如何提高读取条形码的速度？
这里是我到目前为止的代码。
#import "ScanViewController.h"
#import "Utils.h"
#import <AVFoundation/AVFoundation.h>
#import <AudioToolbox/AudioToolbox.h>
@interface ScanViewController ()<AVCaptureMetadataOutputObjectsDelegate>
@property (nonatomic, readwrite) AVCaptureSession *captureSession;
@property (nonatomic, readwrite) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@property (nonatomic, readwrite) UIView *qrCodeFrameView;
@property (nonatomic, readwrite) UILabel *qrCodeTextView;
@property (nonatomic, readwrite) NSArray *supportedCodeTypes;
@property (nonatomic, readwrite) long long lastScanTime;
@property (nonatomic, readwrite) NSString *lastScanCode;
@property (nonatomic, readwrite) AVAudioPlayer *audioPlayer;
@end
@implementation ScanViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.captureSession = [AVCaptureSession new];
self.captureSession.sessionPreset = AVCaptureSessionPresetHigh;
self.supportedCodeTypes = @[AVMetadataObjectTypeUPCECode,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeEAN8Code];
// AVMetadataObjectTypeCode39Code,
// AVMetadataObjectTypeCode39Mod43Code,
// AVMetadataObjectTypeCode93Code,
// AVMetadataObjectTypeCode128Code,
// AVMetadataObjectTypeAztecCode,
// AVMetadataObjectTypePDF417Code,
// AVMetadataObjectTypeITF14Code,
// AVMetadataObjectTypeDataMatrixCode,
// AVMetadataObjectTypeInterleaved2of5Code,
// AVMetadataObjectTypeQRCode];
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVCaptureSessionPre];
if(captureDevice == nil) {
NSLog(@"Failed to get the camera device");
return;
}
@try {
// Get an instance of the AVCaptureDeviceInput class using the previous device object.
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:nil];
// Set the input device on the capture session.
[self.captureSession addInput:input];
// Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
[self.captureSession addOutput:captureMetadataOutput];
// Set delegate and use the default dispatch queue to execute the call back
[captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
captureMetadataOutput.metadataObjectTypes = self.supportedCodeTypes;
// captureMetadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.qr]
} @catch (NSException *error) {
// If any error occurs, simply print it out and don't continue any more.
NSLog(@"%@", error);
return;
}
// Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
self.videoPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
self.videoPreviewLayer.videoGravity = kCAGravityResizeAspectFill;
self.videoPreviewLayer.frame = self.view.layer.bounds;
[self.view.layer addSublayer:self.videoPreviewLayer];
// Start video capture.
[self.captureSession startRunning];
// Move the result view and loading view to the front
[self.view bringSubviewToFront:self.resultView];
[self.view bringSubviewToFront:self.loadingView];
// Initialize QR Code Frame to highlight the QR code
self.qrCodeFrameView = [[UIView alloc] init];
if (self.qrCodeFrameView) {
self.qrCodeFrameView.layer.borderColor = UIColor.greenColor.CGColor;
self.qrCodeFrameView.layer.borderWidth = 2;
[self.view addSubview:self.qrCodeFrameView];
[self.view bringSubviewToFront:self.qrCodeFrameView];
}
self.qrCodeTextView = [[UILabel alloc] init];
if (self.qrCodeTextView) {
[self.qrCodeTextView setTextColor:UIColor.greenColor];
[self.qrCodeTextView setFont:[UIFont systemFontOfSize:20]];
[self.qrCodeFrameView addSubview:self.qrCodeTextView];
}
[self rotateLoadingImage];
[self setResultType:RESULT_TYPE_WORKING codeContent:@"Ready" price:0.00];
[self.loadingView setHidden:YES];
}
-(void)viewWillDisappear:(BOOL)animated {
if (self.audioPlayer != nil) {
[self.audioPlayer stop];
self.audioPlayer = nil;
}
[super viewWillDisappear:animated];
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
-(void) updatePreviewLayer:(AVCaptureConnection*)layer orientation:(AVCaptureVideoOrientation)orientation {
layer.videoOrientation = orientation;
self.videoPreviewLayer.frame = self.view.bounds;
}
-(void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
if(self.videoPreviewLayer.connection != nil) {
UIDevice *currentDevice = [UIDevice currentDevice];
UIDeviceOrientation orientation = [currentDevice orientation];
AVCaptureConnection *previewLayerConnection = self.videoPreviewLayer.connection;
if(previewLayerConnection.isVideoOrientationSupported) {
switch (orientation) {
case UIDeviceOrientationPortrait:
[self updatePreviewLayer:previewLayerConnection orientation:AVCaptureVideoOrientationPortrait];
break;
case UIDeviceOrientationLandscapeRight:
[self updatePreviewLayer:previewLayerConnection orientation:AVCaptureVideoOrientationLandscapeLeft];
break;
case UIDeviceOrientationLandscapeLeft:
[self updatePreviewLayer:previewLayerConnection orientation:AVCaptureVideoOrientationLandscapeRight];
break;
case UIDeviceOrientationPortraitUpsideDown:
[self updatePreviewLayer:previewLayerConnection orientation:AVCaptureVideoOrientationPortraitUpsideDown];
break;
default:
[self updatePreviewLayer:previewLayerConnection orientation:AVCaptureVideoOrientationPortrait];
break;
}
}
}
}
-(void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
// Check if the metadataObjects array is not nil and it contains at least one object.
if (metadataObjects.count == 0) {
self.qrCodeFrameView.frame = CGRectZero;
return;
}
// Get the metadata object.
AVMetadataMachineReadableCodeObject *metadataObj = (AVMetadataMachineReadableCodeObject*)(metadataObjects[0]);
if ([self.supportedCodeTypes containsObject:metadataObj.type]) {
// If the found metadata is equal to the QR code metadata (or barcode) then update the status label's text and set the bounds
AVMetadataObject *barCodeObject = [self.videoPreviewLayer transformedMetadataObjectForMetadataObject:metadataObj];
NSString *code = metadataObj.stringValue;
if (code != nil) {
// check upc a code
if ([self checkUpcACode:metadataObj.type code:code] == NO) {
self.qrCodeTextView.text = @"";
return;
}
int i=0;
for (i=0; i<code.length; i++) {
char ch = [code characterAtIndex:i];
if (ch != '0') break;
}
if (i>0) i--;
code = [code substringFromIndex:i];
self.qrCodeFrameView.frame = barCodeObject.bounds;
[self.qrCodeTextView setText:code];
self.qrCodeTextView.frame = CGRectMake(0, self.qrCodeFrameView.frame.size.height-20, self.qrCodeFrameView.frame.size.width, 20);
NSLog(@"%@", code);
[self handleBarcode:code];
} else {
self.qrCodeTextView.text = @"";
}
}
}
-(BOOL)checkUpcACode:(AVMetadataObjectType)type code:(NSString*)code {
if (type == AVMetadataObjectTypeEAN13Code) {
if ([code hasPrefix:@"0"] && [code length] > 0) {
return YES;
}
}
return NO;
}
@end```
解决方案来自苹果论坛上的PBK
//更改[self handleBarcode：code];
//到
dispatch_async(dispatch_get_main_queue(), ^{
[self handleBarcode:code];
});