IOS-闪光灯操作

AVCaptureDevice.h主要用来获取iphone一些关于相机设备的属性。
前置和后置摄像头
enum {
AVCaptureDevicePositionBack                = 1,
AVCaptureDevicePositionFront               = 2
};
typedef NSInteger AVCaptureDevicePosition;

闪光灯开关
 
enum {
AVCaptureFlashModeOff  = 0,
AVCaptureFlashModeOn   = 1,
AVCaptureFlashModeAuto = 2
};
typedef NSInteger AVCaptureFlashMode;

手电筒开关
 
enum {
AVCaptureTorchModeOff  = 0,
AVCaptureTorchModeOn   = 1,
AVCaptureTorchModeAuto = 2,
};
typedef NSInteger AVCaptureTorchMode;

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

曝光量调节
 
enum {
AVCaptureExposureModeLocked = 0,
AVCaptureExposureModeAutoExpose = 1,
AVCaptureExposureModeContinuousAutoExposure = 2,
};
typedef NSInteger AVCaptureExposureMode;

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

开启闪光灯：

AVCaptureDevice* d = nil; // find a device by position 
NSArray* allDevices = [AVCaptureDevice devices]; 
for (AVCaptureDevice* currentDevice in allDevices) {   
    if (currentDevice.position == AVCaptureDevicePositionBack) { 
            d = currentDevice;   
    } 
} // at this point, d may still be nil, assuming we found something we like.... 
NSError* err = nil; 
BOOL lockAcquired = [d lockForConfiguration:&err]; 
if (!lockAcquired) {    
    // log err and handle... 
} else {    
    // flip on the flash mode    
    if ([d hasFlash] && [d isFlashModeSupported:AVCaptureFlashModeOn] ) {       
    [d setFlashMode:AVCaptureFlashModeOn];    
    }    
    [d unlockForConfiguration]; 
}