直到将相机从 Qr 代码移开才播放音频 - iOS

Question

我是 iOS development 的新手，我正在开发一个应用程序，我想在检测到 QR code 时播放一些音频。我能够检测到 QR code 并播放音频，但问题是当我将相机从 QR code 移开时仅播放音频。因此，如果我将相机指向 QR code，它不会播放音频，但只要我移动相机（即没有检测到 QR code），音频就会开始播放。我不希望这种行为，我希望在检测到 QR code 后立即播放音频。任何建议都会很棒，因为我刚开始 iOS development 2 3 天前。谢谢。

-(void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection(AVCaptureConnection *)connection{



NSString *detected=@"";



if (metadataObjects != nil && [metadataObjects count] > 0) {



    AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];



    if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {


        detected=[NSString stringWithString:[metadataObj stringValue]];

        NSString *path =  [[NSBundle mainBundle] pathForResource:@"cbp"  ofType:@"mp3"];

        NSURL *url = [NSURL URLWithString:path];



        _audioPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:url error:NULL];


        [_audioPlayer play];


    }



}

}

Answer 1

不要在这个 AVFoundation 委托方法中初始化 AVAudioPlayer，扫描开始前用声音文件加载播放器。

(void)loadSound{
    NSString *beepFilePath = [[NSBundle mainBundle] pathForResource:@"cbp" ofType:@"mp3"];
    NSURL *beepURL = [NSURL URLWithString:beepFilePath];
    NSError *error;

    _audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:beepURL error:&error];
    if (error) {
        NSLog(@"Could not play sound file.");
        NSLog(@"%@", [error localizedDescription]);
    }
    else{
        [_audioPlayer prepareToPlay];
    }
}

您可以在 viewWillAppear() method.And 中调用 loadSound() 函数，您的 AVFoundation 委托方法将如下所示：-

(void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection(AVCaptureConnection *)connection{
NSString *detected=@"";

if (metadataObjects != nil && [metadataObjects count] > 0) {

    AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];

    if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {
        detected=[NSString stringWithString:[metadataObj stringValue]];    

        if (_audioPlayer) {
            [_audioPlayer play];
        }
    }
}
}

试试这个。

直到将相机从 Qr 代码移开才播放音频 - iOS

Audio not playing until moving the camera away from Qr code - iOS

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