打开 iPhone 上的手电筒/闪光灯

Question

我知道在 iPhone 4 上打开闪光灯并保持打开状态的唯一方法是打开摄像机。不过我不太确定代码。这就是我正在尝试的：

-(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;
    }   
}

有人知道这是否有效或者我错过了什么吗？ （我还没有 iPhone 4 来测试 - 只是尝试一些新的 API）。

谢谢

Answer 1

您现在可以使用以下较短版本来打开或关闭灯：

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

更新：（2015 年 3 月）

使用 iOS 6.0 及更高版本，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];
    }
}

您可能还想监控从 setTorchModeOnWithLevel: 返回值 (success)。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。

Answer 2

iWasRobbed 的答案很好，除了有一个 AVCaptureSession 一直在后台运行。根据 Instrument 的数据，在我的 iPhone 4s 上，它占用了大约 12% 的 CPU 电量，因此我的应用程序在一分钟内消耗了大约 1% 的电量。换句话说，如果该设备准备用于 AV 捕获，那么它的价格并不便宜。

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

该代码在任何设备上都可以正常工作（在 3GS（无闪存）和 4s 上进行了测试）。也在模拟器中的 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];
        }
    }
}

Answer 3

在下面查看更好的答案： https://stackoverflow.com/a/10054088/308315

---

旧答案：

首先，在您的 AppDelegate .h 文件中：

#import <AVFoundation/AVFoundation.h>

@interface AppDelegate : NSObject <UIApplicationDelegate> {

    AVCaptureSession *torchSession;

}

@property (nonatomic, retain) AVCaptureSession * torchSession;

@end

然后在您的 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;
}

然后，只要您想打开它，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];

}

与关闭它类似：

// 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];
}

Answer 4

lockforConfiguration 在您的代码中设置，您在其中声明 AVCaptureDevice 是一个属性。

[videoCaptureDevice lockForConfiguration:nil];

Answer 5

从 iOS 6.0 及更高版本开始，切换手电筒闪光灯开/关，

- (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];
    }
}

PS 仅当您没有开/关功能时才建议使用此方法。请记住，还有一个选项自动。即AVCaptureFlashModeAuto和AVCaptureTorchModeAuto。为了支持自动模式，您需要跟踪当前模式并根据该模式更改闪光灯和闪光灯模式。火炬。

Answer 6

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
        }
    }
}

Answer 7

//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];
}

Answer 8

这项工作非常好..希望它对某人有帮助！

-(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];
        }
    }
}