iOS Torch level on iPhone 11 Pro

Question

I'm using the AVCaptureDevice.setTorchModeOn(level) method to turn on the flashlight with adjustable brightness.

It functions properly on my outdated iPhone SE; as I move from level 0 to level 1, I can plainly see the four distinct brightness levels.

However, the iPhone 11 Pro's flashlight doesn't activate until level 1.0! And while not at its brightest, it is still visible (compared to a flashlight from Control Center).

Although I used the maxAvailableTorchLevel constant, the outcomes were the same as when I used 1.0.
Additionally, attempted values greater than 1.0 produce an error (as expected).

Did anyone else experience this issue? Perhaps there are some solutions?

Answer 1

I recalled that there was no straightforward LED API back when iOS 3.x was in use. A whole video capture session had to be started. It turns out that this is the only option for the iPhone 11; however. If you know of any that don't call for this, please let me know.

This is the fix I've tried. Because I used Objective C rather than Swift in this older project from 2009, I'm utilising it here. You can quickly locate Swift code to begin video capturing (ignore the output; it should still function properly).

AVCaptureSession* session = [[AVCaptureSession alloc] init];

AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];
if ([session canAddInput:deviceInput]) {
    [session addInput:deviceInput];
}

AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
[previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

CALayer *rootLayer = self.view.layer;
[rootLayer setMasksToBounds:YES];

CGRect frame = self.view.frame;
[previewLayer setFrame:frame];
[rootLayer insertSublayer:previewLayer atIndex:0];

//This is where you'd save the video with AVCaptureVideoDataOutput but of course we don't.

[session startRunning];

And after this you just start the LED as usual:

NSError *error = nil;

if ([inputDevice isTorchModeSupported:AVCaptureTorchModeOn])
[inputDevice setTorchModeOnWithLevel:1.0 error:&error];

This gets maximum brightness on my iPhone 11 Pro. I am now looking for the same solution without having to use the video capture (which obviously uses battery AND requires a permission, which users may not like. It needs to be explained well).