I remembered that back in the iOS 3.x days we didn't have simple LED API. We had to start a full video capture session. Well it turns out that with the iPhone 11 this seems to be the only solution. I'd love to hear about others which don't require this.
This is my tested workaround. I am using Objective C here, not Swift because that's what I used in this old app from 2009! You can easily find Swift code to start video capture (and ignore the output, it should work the same.
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).
