I'm developing an iOS app using AVFoundation for real-time video capture and object detection.
While implementing torch functionality with camera switching (between Wide and Ultra-Wide lenses), I encountered a critical issue where the camera freezes when toggling the torch while the Ultra-Wide camera is active.
Issue
If the torch is ON and I switch from Wide to Ultra-Wide, the camera freezes
If the Ultra-Wide camera is active and I try to turn the torch ON, the camera freezes
The iPhone Camera app allows using the torch while recording video with the Ultra-Wide lens, so this should be possible via AVFoundation as well.
Code snippet
DispatchQueue.global(qos: .userInitiated).async { [weak self] in
guard let self = self else { return }
let isSwitchingToUltraWide = !self.isUsingFisheyeCamera
let cameraType: AVCaptureDevice.DeviceType = isSwitchingToUltraWide ? .builtInUltraWideCamera : .builtInWideAngleCamera
let cameraName = isSwitchingToUltraWide ? "Ultra Wide" : "Wide"
guard let selectedCamera = AVCaptureDevice.default(cameraType, for: .video, position: .back) else {
DispatchQueue.main.async {
self.showAlert(title: "Camera Error", message: "\(cameraName) camera is not available on this device.")
}
return
}
do {
let currentInput = self.videoCapture.captureSession.inputs.first as? AVCaptureDeviceInput
self.videoCapture.captureSession.beginConfiguration()
if isSwitchingToUltraWide && self.isFlashlightOn {
self.forceEnableTorchThroughWide()
}
if let currentInput = currentInput {
self.videoCapture.captureSession.removeInput(currentInput)
}
let videoInput = try AVCaptureDeviceInput(device: selectedCamera)
self.videoCapture.captureSession.addInput(videoInput)
self.videoCapture.captureSession.commitConfiguration()
self.videoCapture.updateVideoOrientation()
DispatchQueue.main.async {
if let barButton = sender as? UIBarButtonItem {
barButton.title = isSwitchingToUltraWide ? "Wide" : "Ultra Wide"
barButton.tintColor = isSwitchingToUltraWide ? UIColor.systemGreen : UIColor.white
}
print("Switched to \(cameraName) camera.")
}
self.isUsingFisheyeCamera.toggle()
} catch {
DispatchQueue.main.async {
self.showAlert(title: "Camera Error", message: "Failed to switch to \(cameraName) camera: \(error.localizedDescription)")
}
}
}
}
Expected Behavior
Torch should be able to work when Ultra-Wide is active, just like the iPhone Camera app does.
The camera should not freeze when switching between Wide and Ultra-Wide with the torch ON.
AVCaptureSession should not crash when toggling the torch while Ultra-Wide is active.
Questions & Help Needed
Is this a known issue with AVFoundation?
How does the iPhone Camera app allow using the torch while recording in Ultra-Wide?
What’s the correct way to switch between Wide and Ultra-Wide cameras without freezing when the torch is active?
Info
Device tested: iPhone 13 Pro / iPhone 15 Pro / Iphone 15
iOS Version: iOS 17.3 / iOS 18.0
Xcode Version: 16.2
