ios 在 iPhone 上打开手电筒/闪光灯

Turn on torch/flash on iPhone

提问by John

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:

我知道在 iPhone 4 上开启闪光灯并保持开启的唯一方法是打开摄像机。虽然我不太确定代码。这是我正在尝试的：

-(IBAction)turnTorchOn {
    AVCaptureSession *captureSession = [[AVCaptureSession alloc] init];
    AVCaptureDevice *videoCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    NSError *error = nil;
    AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoCaptureDevice error:&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).

有谁知道这是否可行，或者我错过了什么？（我还没有要测试的 iPhone 4 - 只是尝试一些新的 API）。

Thanks

谢谢

采纳答案by Gustavo Barrientos

the lockforConfigurationis set in your code, where you declare your AVCaptureDeviceis a property.

将lockforConfiguration在你的代码，你宣布你的设置AVCaptureDevice是一个属性。

[videoCaptureDevice lockForConfiguration:nil];

回答by mahboudz

Here's a shorter version you can now use to turn the light on or off:

这是一个较短的版本，您现在可以用来打开或关闭灯：

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch]) {
    [device lockForConfiguration:nil];
    [device setTorchMode:AVCaptureTorchModeOn];  // use AVCaptureTorchModeOff to turn off
    [device unlockForConfiguration];
}

UPDATE: (March 2015)

更新：（2015 年 3 月）

With iOS 6.0 and later, you can control the brightness or level of the torch using the following method:

在 iOS 6.0 及更高版本中，您可以使用以下方法控制手电筒的亮度或级别：

- (void)setTorchToLevel:(float)torchLevel
{
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([device hasTorch]) {
        [device lockForConfiguration:nil];
        if (torchLevel <= 0.0) {
            [device setTorchMode:AVCaptureTorchModeOff];
        }
        else {
            if (torchLevel >= 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 AVCaptureMaxAvailableTorchLevelwill set the level to the highest level that is allowed given the temperature of the torch.

您可能还想监视来自 的返回值 ( success) setTorchModeOnWithLevel:。如果您尝试将级别设置得太高并且割炬过热，则可能会失败。在这种情况下，将级别设置为AVCaptureMaxAvailableTorchLevel会将级别设置为给定割炬温度所允许的最高级别。

回答by Tibidabo

iWasRobbed's answer is great, except there is an AVCaptureSessionrunning in the background all the time. On my iPhone 4s it takes about 12% CPU poweraccording 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.

iWasRobbed 的回答很好，只是有一个AVCaptureSession一直在后台运行。根据 Instrument 的数据，在我的 iPhone 4s 上它需要大约 12% 的 CPU 电量，所以我的应用程序在一分钟内消耗了大约 1% 的电池电量。换句话说，如果该设备准备用于 AV 捕获，它并不便宜。

Using the code below my app requires 0.187% a minute so the battery life is more than 5x longer.

使用我的应用程序下面的代码每分钟需要 0.187%，因此电池寿命延长了 5 倍以上。

This code works just fine on any device (tested on both 3GS (no flash) and 4s). Tested on 4.3 in simulator as well.

此代码在任何设备上都可以正常工作（在 3GS（无闪存）和 4s 上测试）。也在模拟器中在 4.3 上进行了测试。

#import <AVFoundation/AVFoundation.h>

- (void) turnTorchOn:(BOOL)on {

    Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
    if (captureDeviceClass != nil) {
        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
        if ([device hasTorch] && [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];
        }
    }
}

回答by iwasrobbed

See a better answer below:https://stackoverflow.com/a/10054088/308315

请参阅下面的更好答案：https : //stackoverflow.com/a/10054088/308315

---

---

Old answer:

旧答案：

First, in your AppDelegate .h file:

首先，在你的 AppDelegate .h 文件中：

#import <AVFoundation/AVFoundation.h>

@interface AppDelegate : NSObject <UIApplicationDelegate> {

    AVCaptureSession *torchSession;

}

@property (nonatomic, retain) AVCaptureSession * torchSession;

@end

Then in your AppDelegate .m file:

然后在你的 AppDelegate .m 文件中：

@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] && [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:

然后，无论何时您想打开它，只需执行以下操作：

// 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:

和关闭它类似：

// 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];
}

回答by Hemang

From iOS 6.0 and above, toggling torch flash on/off,

从 iOS 6.0 及更高版本开始，打开/关闭手电筒闪光灯，

- (void) toggleFlash {
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([device hasTorch] && [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. AVCaptureFlashModeAutoand AVCaptureTorchModeAuto. To support auto mode as well, you've keep track of current mode and based on that change mode of flash & torch.

PS 这种方法仅在您没有开/关功能时才建议使用。记住还有一个选择Auto。即AVCaptureFlashModeAuto和AVCaptureTorchModeAuto。为了也支持自动模式，您必须跟踪当前模式并基于闪光灯和手电筒的更改模式。

回答by Avt

Swift 2.0 version:

斯威夫特 2.0 版本：

func setTorchLevel(torchLevel: Float)
{
    self.captureSession?.beginConfiguration()
    defer {
        self.captureSession?.commitConfiguration()
    }

    if let device = backCamera?.device where device.hasTorch && device.torchAvailable {
        do {
            try device.lockForConfiguration()
            defer {
                device.unlockForConfiguration()
            }

            if torchLevel <= 0.0 {
                device.torchMode = .Off
            }
            else if torchLevel >= 1.0 {
                try device.setTorchModeOnWithLevel(min(torchLevel, AVCaptureMaxAvailableTorchLevel))
            }
        }
        catch let error {
            print("Failed to set up torch level with error \(error)")
            return
        }
    }
}

回答by Rushabh

//import fremework in .h file 

#import <AVFoundation/AVFoundation.h>
{
 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] && [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];
}

回答by Jonas

This work's very well.. hope it help's someone !

这项工作非常好..希望对某人有所帮助！

-(IBAction)flashlight:(id)sender {

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    if ([device hasTorch] && [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];
        }
    }
}