iOS手电筒（AVCaptureDevice）

AVCaptureDevice主要用来获取iPhone一些关于相机设备的相关属性。

必须引用一个AVFoundation框架：
//#import <AVFoundation/AVFoundation.h>

1.前置和后置摄像头

typedef NS_ENUM(NSInteger, AVCaptureDevicePosition) {
AVCaptureDevicePositionUnspecified = 0,
AVCaptureDevicePositionBack = 1,
AVCaptureDevicePositionFront = 2
} NS_AVAILABLE(10_7, 4_0);

2.闪光灯开关

typedef NS_ENUM(NSInteger, AVCaptureFlashMode) {
AVCaptureFlashModeOff = 0,
AVCaptureFlashModeOn = 1,
AVCaptureFlashModeAuto = 2

} NS_AVAILABLE(10_7, 4_0);

3.手电筒开关--其实就是相机的闪光灯

typedef NS_ENUM(NSInteger, AVCaptureTorchMode) {
AVCaptureTorchModeOff = 0,
AVCaptureTorchModeOn = 1,
AVCaptureTorchModeAuto = 2,

} NS_AVAILABLE(10_7, 4_0);

4.焦距模式调整

typedef NS_ENUM(NSInteger, AVCaptureFocusMode) {
AVCaptureFocusModeLocked = 0,
AVCaptureFocusModeAutoFocus = 1,
AVCaptureFocusModeContinuousAutoFocus = 2,

} NS_AVAILABLE(10_7, 4_0);

5.曝光量调节

typedef NS_ENUM(NSInteger, AVCaptureExposureMode) {
AVCaptureExposureModeLocked = 0,
AVCaptureExposureModeAutoExpose = 1,
AVCaptureExposureModeContinuousAutoExposure = 2,
AVCaptureExposureModeCustom NS_ENUM_AVAILABLE_IOS(8_0) = 3,

} NS_AVAILABLE(10_7, 4_0);

6.白平衡

typedef NS_ENUM(NSInteger, AVCaptureWhiteBalanceMode) {
AVCaptureWhiteBalanceModeLocked = 0,
AVCaptureWhiteBalanceModeAutoWhiteBalance = 1,
AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2,
} NS_AVAILABLE(10_7, 4_0);

7.距离调整

typedef NS_ENUM(NSInteger, AVCaptureAutoFocusRangeRestriction) {
AVCaptureAutoFocusRangeRestrictionNone = 0,
AVCaptureAutoFocusRangeRestrictionNear = 1,
AVCaptureAutoFocusRangeRestrictionFar = 2,

} NS_AVAILABLE_IOS(7_0);

下面简单实现以下手电筒的如何开启和关闭，为了简单起见，我们就借助touchesBegan方法操作，通过触摸屏幕开启和关闭手电筒

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()
@property (nonatomic, strong) AVCaptureDevice *device;
@property (nonatomic,assign) BOOL lightOn;
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    /**
     *  hasTorch :返回YES表名手机上有手电筒
     */
    
    if (![_device hasTorch]) {
        NSLog(@"手电筒坏了");
        return;
    }
    
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    
    _lightOn = !_lightOn;
    
    //根据ligthOn状态判断打开还是关闭
    if (_lightOn) {
        //开启手电筒
        [_device lockForConfiguration:nil];
        
        [_device setTorchMode:AVCaptureTorchModeOn];
        
        [_device unlockForConfiguration];
        
    }else{
        //关闭手电筒
        [_device lockForConfiguration:nil];
        
        [_device setTorchMode:AVCaptureTorchModeOff];
        
        [_device unlockForConfiguration];
        
    }
    
}

@end

还有其他很多功能 ，后续有时间再更新，请记得用真机测试哦！