I'm working on an iOS-app where one of the features is scanning QR-codes. For this I'm using the excellent library, ZBar. The scanning works fine and is generally really quick. However when you use smaller QR-codes it takes a bit longer to scan, mostly due to the fact that the autofocus needs some time to adjust. I was experimenting and noticed that the focus could be locked using the following code:
AVCaptureDevice *cameraDevice = readerView.device;
if ([cameraDevice lockForConfiguration:nil]) {
[cameraDevice setFocusMode:AVCaptureFocusModeLocked];
[cameraDevice unlockForConfiguration];
}
When this code is used after a successful scan, the coming scans are really quick. That made me wonder, could I somehow lock the focus before even scanning one code? The app will only scan rather small QR-codes so there will never be a need for focusing on something far away. Sure, I could implement something like tap to focus, but preferably I would like to avoid that extra step. Is there a way to achieve this? Or are there maybe another way of speeding things up when dealing with smaller QR-codes?
// Alexander