UIWebView屏幕点击区域在显示然后隐藏UIView叠加层后停止工作

Question

我一直在开发一个具有全屏UIWebView的应用程序，其中包含一个基于HTML的应用程序。它具有使用 JS 和本机 Obj-C 代码之间的本机桥接进行工作 QR 码扫描的功能。点击一个按钮会启动这个 UIView，它的大小大约是整个显示屏的一半，作为叠加层，在其中你会看到视频源，当检测到二维码时，它会传回代码并关闭 UIView。这很有效。

然而，UIWebview随后遇到了一个奇怪的问题，任何本来在UIView下面的元素都变得无法点击。就好像UIView的幽灵仍然存在一样。

知道为什么会发生这种情况吗？

- (void)handleCall:(NSString*)functionName callbackId:(int)callbackId args:(NSArray*)args
{
    if ([functionName isEqualToString:@"setBackgroundColor"]) {
       ....... SNIP ........
}
else if ([functionName isEqualToString:@"scanQRCode"]) {
    _viewPreview = [[UIView alloc] initWithFrame:CGRectMake(256, 192, 512, 384)];
    [self addSubview:self.viewPreview];
    [self bringSubviewToFront:_viewPreview];
    _captureSession = nil;
    if (!_isReading) {
      if ([self startReading]) {
        NSLog(@"Read barcode: %@", @"started");
      }
    }
    else{
      [self stopReading];
      [_viewPreview removeFromSuperview];
      [_viewPreview release];

    }
    _isReading = !_isReading;
  }
  else
  {
    NSLog(@"Unimplemented method '%@'",functionName);
   [uniReader requestSwipe];
   [self returnResult:callbackId args:nil];  
  }
}
- (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:AVMetadataObjectTypeQRCode]];
  _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc]    initWithSession:_captureSession];
 [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
 [_videoPreviewLayer setFrame:_viewPreview.layer.bounds];
 [_viewPreview.layer addSublayer:_videoPreviewLayer];
 // Since the app is landscape only, it is necessary to rotate the preview view to match
 [_videoPreviewLayer.connection setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];
 // Start video capture.
 [_captureSession startRunning];
 return YES;

}

 -(void)stopReading{
 [_captureSession stopRunning];
 _captureSession = nil;
    NSLog(@"Read barcode: %@", @"Stop scanning");
 [_videoPreviewLayer removeFromSuperlayer];

}

   -(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 && [metadataObjects count] > 0) {
 // Get the metadata object.
 AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
 NSString *barcodeString = metadataObj.stringValue;
 NSLog(@"Detected QR: %@", barcodeString);
NSString *javaScript = [NSString stringWithFormat:@"setQR('%@')", barcodeString];
if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {
  // 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.
  [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];
  _isReading = NO;
  [self performSelectorOnMainThread:@selector(stringByEvaluatingJavaScriptFromString:) withObject:javaScript waitUntilDone:NO];
}

} }

@end

Answer 1

scanQRCode 是否调用了两次：一次用于添加，一次用于删除覆盖？如果是这样，那么您总是在开始时添加新的叠加视图。任何 stopReading 都会从其超级视图（原始叠加层）中删除正在运行的视频，然后从屏幕上删除最新的叠加层。这将使原始覆盖窗口没有内容，这可能是您的问题？