AVCaptureDevice.h主要用来获取iPhone一些关于相机设备的属性。

①前置和后置摄像头

enum {
AVCaptureDevicePositionBack                = 1,
AVCaptureDevicePositionFront               = 2
};
typedef NSInteger AVCaptureDevicePosition;

判断设备是否有摄像头

-(BOOL) isCameraAvailable{
 return [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];
}

判断前摄像头是否有用

- (BOOL) isFrontCameraAvailable{
  return [UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront];
}

判断后摄像头是否有用

- (BOOL) isRearCameraAvailable{
  return [UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear];
}

切换摄像头

- (BOOL) hasMultipleCameras {
  NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
  if (devices != nil && [devices count] > 1) return YES;
  return NO;
}
- (AVCaptureDevice *)cameraWithPosition : (AVCaptureDevicePosition)position{
  NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
  for (AVCaptureDevice *device in devices ){
      if ( device.position == position )return device;
      return nil ;
  }
}
- (void) swapFrontAndBackCameras {
  if (![self hasMultipleCameras]) return;
  NSArray *inputs = self.captureSession.inputs;
  for ( AVCaptureDeviceInput *captureDeviceInput in inputs ) {
      AVCaptureDevice *device = captureDeviceInput.device ;
      if ( [device hasMediaType:AVMediaTypeVideo ] ) {
          AVCaptureDevicePosition position = device.position ;
          AVCaptureDevice *newCamera = nil ;
          AVCaptureDeviceInput *newInput = nil ;
          if (position == AVCaptureDevicePositionFront){
              newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack];
          }else{
              newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront];
          }
          newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil];
          [self.captureSession beginConfiguration ];
          [self.captureSession removeInput:captureDeviceInput]; //remove current
          [self.captureSession addInput:newInput];
          [self.captureSession commitConfiguration];
          break ;
     }
  }
}

②闪光灯开关

enum {
AVCaptureFlashModeOff  = 0,
AVCaptureFlashModeOn   = 1,
AVCaptureFlashModeAuto = 2
};
typedef NSInteger AVCaptureFlashMode;

开启闪光灯

AVCaptureDevice* device = nil; 
NSArray* allDevices = [AVCaptureDevice devices]; 
for (AVCaptureDevice* currentDevice in allDevices) {   
    if (currentDevice.position == AVCaptureDevicePositionBack) { 
        device = currentDevice;   
    } 
}
NSError* err = nil; 
BOOL lockAcquired = [device lockForConfiguration:&err]; 
if (!lockAcquired) {    
    // 此设备不支持或其他原因 
} else {    
    // 打开闪光模式    
    if ([device hasFlash] && [device isFlashModeSupported:AVCaptureFlashModeOn] ) {       
        [device setFlashMode:AVCaptureFlashModeOn];    
    }    
    [device unlockForConfiguration]; 
}

③手电筒开关

enum {
AVCaptureTorchModeOff  = 0,
AVCaptureTorchModeOn   = 1,
AVCaptureTorchModeAuto = 2,
};
typedef NSInteger AVCaptureTorchMode;

切换手电筒开关

- (void)isOpenFlashLight:(UIButton *)btn{
  self.isOpenFlashlight = !self.isOpenFlashlight;
  AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
  if (self.isOpenFlashlight) {
    if (device.torchMode == AVCaptureTorchModeOff) {//torch手电筒模式
        [device lockForConfiguration:nil];//设备锁
        [device setTorchMode:AVCaptureTorchModeOn];//手电筒打开
        [device unlockForConfiguration];//不需要自动调用
    }
}else{
    if (device.torchMode == AVCaptureTorchModeOn) {
        
        [device lockForConfiguration:nil];
        [device setTorchMode:AVCaptureTorchModeOff];
        [device unlockForConfiguration];
    }
}
}

④焦距

enum {
AVCaptureFocusModeLocked              = 0,
AVCaptureFocusModeAutoFocus           = 1,
AVCaptureFocusModeContinuousAutoFocus = 2,
};
typedef NSInteger AVCaptureFocusMode;

调整焦距

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <MobileCoreServices/MobileCoreServices.h>

#define XBScreenWidth   [UIScreen mainScreen].bounds.size.width
#define XBScreenHeight   [UIScreen mainScreen].bounds.size.height

@interface ViewController ()<AVCaptureVideoDataOutputSampleBufferDelegate>

@property (strong, nonatomic) AVCaptureSession *avSession;
@property (strong, nonatomic) AVCaptureDevice *backCameraDevice;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setupSession];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    if (!_avSession.isRunning) {
        [_avSession startRunning];
    }
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    if (_avSession.isRunning) {
        [_avSession stopRunning];
    }
}

- (AVCaptureDevice *)backCamera
{
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if (device.position == AVCaptureDevicePositionBack) {
            return device;
        }
    }
    return nil;
}

- (void)setupSession
{
    //创建session会话
    _avSession = [[AVCaptureSession alloc] init];
    [_avSession beginConfiguration];
    _avSession.sessionPreset = AVCaptureSessionPreset640x480;
    //通过capture对象创建输入设备对象
    NSError *error = nil;
    _backCameraDevice = [self backCamera];
    [_backCameraDevice lockForConfiguration:&error];
    _backCameraDevice.focusMode = AVCaptureFocusModeLocked;
    [_backCameraDevice unlockForConfiguration];
    AVCaptureDeviceInput *inputDevice = [AVCaptureDeviceInput deviceInputWithDevice:_backCameraDevice error:&error];
    //将输入设备添加到会话
    if ([_avSession canAddInput:inputDevice]) {
        [_avSession addInput:inputDevice];
    }else{
        NSLog(@"不能添加视频输入设备");
        return;
    }
    //添加一个输出设备
    AVCaptureVideoDataOutput *videoOutput = [[AVCaptureVideoDataOutput alloc] init];
    videoOutput.videoSettings = @{(__bridge NSString *)kCVPixelBufferPixelFormatTypeKey : [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]};

    videoOutput.alwaysDiscardsLateVideoFrames = YES;

    if ([_avSession canAddOutput:videoOutput]) {
        [_avSession addOutput:videoOutput];
    }else{
        NSLog(@"不能添加视频输出设备");
        return;
    }

    AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:_avSession];
    //只有设置GravityResizeAspectFill或GravityResize，然后设置frame才有效，图像不会按照frame的大小显示
   previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
   previewLayer.frame = CGRectMake(0, 20, 320, 240);
   [self.view.layer addSublayer:previewLayer];

   [_avSession commitConfiguration];
}

//UISlider 绑定的方法

- (IBAction)foucsChange:(UISlider *)sender {
    NSError *error = nil;
    [_backCameraDevice lockForConfiguration:&error];
    [_backCameraDevice setFocusModeLockedWithLensPosition:sender.value completionHandler:nil];
    [_backCameraDevice unlockForConfiguration]; 
}

⑤曝光量调整

enum {
AVCaptureExposureModeLocked = 0,
AVCaptureExposureModeAutoExpose = 1,
AVCaptureExposureModeContinuousAutoExposure = 2,
};
typedef NSInteger AVCaptureExposureMode;

⑥白平衡

enum {
AVCaptureWhiteBalanceModeLocked         = 0,
AVCaptureWhiteBalanceModeAutoWhiteBalance         = 1,
AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2,
};
typedef NSInteger AVCaptureWhiteBalanceMode;