Turn on torch flash on iPhone

Question

I know that the only way to turn on the flash and keep it on on iPhone 4 is by turning the video camera on  I m not too sure of the code though  Here is what I am trying   - IBAction turnTorchOn       AVCaptureSession  captureSession     AVCaptureSession alloc  init       AVCaptureDevice  videoCaptureDevice    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo       NSError  error   nil      AVCaptureDeviceInput  videoInput    AVCaptureDeviceInput deviceInputWithDevice videoCaptureDevice error  amp error        if  videoInput             captureSession addInput videoInput            AVCaptureVideoDataOutput  videoOutput     AVCaptureVideoDataOutput alloc  init            videoOutput setSampleBufferDelegate self queue dispatch get current queue               captureSession addOutput videoOutput             captureSession startRunning            videoCaptureDevice torchMode   AVCaptureTorchModeOn               Does anybody know if this would work or am I missing anything   I don t have an iPhone 4 yet to test on -just trying out some of the new API s    Thanks

User · Answer

From iOS 6 0 and above  toggling torch flash on off   -  void  toggleFlash       AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo       if   device hasTorch   amp  amp   device hasFlash             device lockForConfiguration nil            device setFlashMode  device flashActive    AVCaptureFlashModeOff   AVCaptureFlashModeOn            device setTorchMode  device torchActive    AVCaptureTorchModeOff   AVCaptureTorchModeOn            device unlockForConfiguration             P S  This approach is only suggestible if you don t have on off function  Remember there s one more option Auto  i e  AVCaptureFlashModeAuto and AVCaptureTorchModeAuto  To support auto mode as well  you ve keep track of current mode and based on that change mode of flash  amp  torch

User · Answer

This work s very well   hope it help s someone    - IBAction flashlight  id sender        AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo        if   device hasTorch   amp  amp   device hasFlash             if  device torchMode    AVCaptureTorchModeOff                  sender setTitle   Torch Off  forState UIControlStateNormal                AVCaptureDeviceInput  flashInput    AVCaptureDeviceInput deviceInputWithDevice device error  nil               AVCaptureVideoDataOutput  output     AVCaptureVideoDataOutput alloc  init                AVCaptureSession  cam     AVCaptureSession alloc  init                 cam beginConfiguration                device lockForConfiguration nil                 device setTorchMode AVCaptureTorchModeOn                device setFlashMode AVCaptureFlashModeOn                 cam addInput flashInput                cam addOutput output                 device unlockForConfiguration                 cam commitConfiguration                cam startRunning                 self setTorchSession cam                     else                sender setTitle   Torch On  forState UIControlStateNormal                 torchSession stopRunning

User · Answer

the lockforConfiguration is set in your code  where you declare your AVCaptureDevice is a property    videoCaptureDevice lockForConfiguration nil

User · Answer

iWasRobbed s answer is great  except there is an AVCaptureSession running in the background all the time  On my iPhone 4s it takes about 12  CPU power according to Instrument so my app took about 1  battery in a minute  In other words if the device is prepared for AV capture it s not cheap    Using the code below my app requires 0 187  a minute so the battery life is more than 5x longer    This code works just fine on any device  tested on both 3GS  no flash  and 4s   Tested on 4 3 in simulator as well    import  lt AVFoundation AVFoundation h gt   -  void  turnTorchOn  BOOL on        Class captureDeviceClass   NSClassFromString   AVCaptureDevice        if  captureDeviceClass    nil            AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo           if   device hasTorch   amp  amp   device hasFlash                  device lockForConfiguration nil               if  on                     device setTorchMode AVCaptureTorchModeOn                    device setFlashMode AVCaptureFlashModeOn                   torchIsOn   YES                else                    device setTorchMode AVCaptureTorchModeOff                    device setFlashMode AVCaptureFlashModeOff                   torchIsOn   NO                                         device unlockForConfiguration

User · Answer

See a better answer below  https   stackoverflow com a 10054088 308315    Old answer   First  in your AppDelegate  h file    import  lt AVFoundation AVFoundation h gt    interface AppDelegate   NSObject  lt UIApplicationDelegate gt         AVCaptureSession  torchSession       property  nonatomic  retain  AVCaptureSession   torchSession    end   Then in your AppDelegate  m file    implementation AppDelegate   synthesize torchSession   -  void dealloc        torchSession release         super dealloc      -  id  init       if   self    super init              initialize flashlight        test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above         Class captureDeviceClass   NSClassFromString   AVCaptureDevice            if  captureDeviceClass    nil                 AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo                if   device hasTorch   amp  amp   device hasFlash                     if  device torchMode    AVCaptureTorchModeOff                     NSLog   Setting up flashlight for later use                            AVCaptureDeviceInput  flashInput    AVCaptureDeviceInput deviceInputWithDevice device error  nil                       AVCaptureVideoDataOutput  output     AVCaptureVideoDataOutput alloc  init                        AVCaptureSession  session     AVCaptureSession alloc  init                     session beginConfiguration                        device lockForConfiguration nil                         session addInput flashInput                        session addOutput output                         device unlockForConfiguration                         output release                     session commitConfiguration                    session startRunning                     self setTorchSession session                    session release                                                              return self      Then anytime you want to turn it on  just do something like this      test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above Class captureDeviceClass   NSClassFromString   AVCaptureDevice    if  captureDeviceClass    nil         AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo         device lockForConfiguration nil         device setTorchMode AVCaptureTorchModeOn        device setFlashMode AVCaptureFlashModeOn         device unlockForConfiguration        And similar for turning it off      test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above Class captureDeviceClass   NSClassFromString   AVCaptureDevice    if  captureDeviceClass    nil         AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo         device lockForConfiguration nil         device setTorchMode AVCaptureTorchModeOff        device setFlashMode AVCaptureFlashModeOff         device unlockForConfiguration

User · Answer

import fremework in  h file    import  lt AVFoundation AVFoundation h gt     AVCaptureSession  torchSession      property nonatomic retain AVCaptureSession  torchSession    - IBAction onoff  id sender     implement in  m file   synthesize torchSession   - IBAction onoff  id sender       AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo       if   device hasTorch   amp  amp   device hasFlash                 if  device torchMode    AVCaptureTorchModeOff                          button setTitle   OFF  forState UIControlStateNormal                AVCaptureDeviceInput  flashInput    AVCaptureDeviceInput deviceInputWithDevice device error  nil                AVCaptureVideoDataOutput  output     AVCaptureVideoDataOutput alloc  init               AVCaptureSession  session     AVCaptureSession alloc  init                 session beginConfiguration                device lockForConfiguration nil                device setTorchMode AVCaptureTorchModeOn                device setFlashMode AVCaptureFlashModeOn                session addInput flashInput                session addOutput output                device unlockForConfiguration                output release                session commitConfiguration                session startRunning                self setTorchSession session                session release                     else                         button setTitle   ON  forState UIControlStateNormal                torchSession stopRunning                      -  void dealloc        torchSession release        super dealloc

User · Answer

Here s a shorter version you can now use to turn the light on or off   AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo   if   device hasTorch          device lockForConfiguration nil        device setTorchMode AVCaptureTorchModeOn       use AVCaptureTorchModeOff to turn off      device unlockForConfiguration       UPDATE   March 2015   With iOS 6 0 and later  you can control the brightness or level of the torch using the following method   -  void setTorchToLevel  float torchLevel       AVCaptureDevice  device    AVCaptureDevice defaultDeviceWithMediaType AVMediaTypeVideo       if   device hasTorch              device lockForConfiguration nil           if  torchLevel  lt   0 0                 device setTorchMode AVCaptureTorchModeOff                     else               if  torchLevel  gt   1 0                  torchLevel   AVCaptureMaxAvailableTorchLevel              BOOL success    device setTorchModeOnWithLevel torchLevel   error nil                      device unlockForConfiguration             You may also want to monitor the return value  success  from setTorchModeOnWithLevel    You may get a failure if you try to set the level too high and the torch is overheating   In that case setting the level to AVCaptureMaxAvailableTorchLevel will set the level to the highest level that is allowed given the temperature of the torch

User · Answer

Swift 2 0 version   func setTorchLevel torchLevel  Float        self captureSession  beginConfiguration       defer           self captureSession  commitConfiguration              if let device   backCamera  device where device hasTorch  amp  amp  device torchAvailable           do               try device lockForConfiguration               defer                   device unlockForConfiguration                              if torchLevel  lt   0 0                   device torchMode    Off                           else if torchLevel  gt   1 0                   try device setTorchModeOnWithLevel min torchLevel  AVCaptureMaxAvailableTorchLevel                                   catch let error               print  Failed to set up torch level with error   error                return

[ios] Turn on torch/flash on iPhone

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