iOS音视频学习9——AVFoundation拍照

UIImagePickerController确实强大，但是与MPMoviePlayerController类似，由于它的高度封装性，要进行某些自定义工作就比较复杂了。例如要做出一款类似于美颜相机的拍照界面就比较难以实现了，此时就可以考虑使用AVFoundation来实现。
AVFoundation中提供了很多现成的播放器和录音机，但是事实上它还有更加底层的内容可以供开发者使用。因为AVFoundation中抽了很多和底层输入、输出设备打交道的类，依靠这些类开发人员面对的不再是封装好的音频播放器AVAudioPlayer、录音机（AVAudioRecorder）、视频（包括音频）播放器AVPlayer，而是输入设备（例如麦克风、摄像头）、输出设备（图片、视频）等。

首先了解一下使用AVFoundation做拍照和视频录制开发用到的相关类：

  • AVCaptureSession：媒体（音、视频）捕获会话，负责把捕获的音视频数据输出到输出设备中。一个AVCaptureSession可以有多个输入输出：
  • AVCaptureDevice：输入设备，包括麦克风、摄像头，通过该对象可以设置物理设备的一些属性（例如相机聚焦、白平衡等）。
  • AVCaptureDeviceInput：设备输入数据管理对象，可以根据AVCaptureDevice创建对应的AVCaptureDeviceInput对象，该对象将会被添加到AVCaptureSession中管理。
  • AVCaptureOutput：输出数据管理对象，用于接收各类输出数据，通常使用对应的子类AVCaptureAudioDataOutput、AVCaptureStillImageOutput、AVCaptureVideoDataOutput、AVCaptureFileOutput，该对象将会被添加到AVCaptureSession中管理。

注意：前面几个对象的输出数据都是NSData类型，而AVCaptureFileOutput代表数据以文件形式输出，类似的，AVCcaptureFileOutput也不会直接创建使用，通常会使用其子类：AVCaptureAudioFileOutput、AVCaptureMovieFileOutput。
当把一个输入或者输出添加到AVCaptureSession之后AVCaptureSession就会在所有相符的输入、输出设备之间建立连接（AVCaptionConnection）：


  • AVCaptureVideoPreviewLayer：相机拍摄预览图层，是CALayer的子类，使用该对象可以实时查看拍照或视频录制效果，创建该对象需要指定对应的AVCaptureSession对象。

使用AVFoundation拍照和录制视频的一般步骤如下：

  1. 创建AVCaptureSession对象。
  2. 使用AVCaptureDevice的静态方法获得需要使用的设备，例如拍照和录像就需要获得摄像头设备，录音就要获得麦克风设备。
  3. 利用输入设备AVCaptureDevice初始化AVCaptureDeviceInput对象。
  4. 初始化输出数据管理对象，如果要拍照就初始化AVCaptureStillImageOutput对象；如果拍摄视频就初始化AVCaptureMovieFileOutput对象。
  5. 将数据输入对象AVCaptureDeviceInput、数据输出对象AVCaptureOutput添加到媒体会话管理对象AVCaptureSession中。
  6. 创建视频预览图层AVCaptureVideoPreviewLayer并指定媒体会话，添加图层到显示容器中，调用AVCaptureSession的startRuning方法开始捕获。
  7. 将捕获的音频或视频数据输出到指定文件。

拍照

下面看一下如何使用AVFoundation实现一个拍照程序，在这个程序中将实现摄像头预览、切换前后摄像头、闪光灯设置、对焦、拍照保存等功能。应用大致效果如下：

应用效果

在程序中定义会话、输入、输出等相关对象。

@interface ViewController ()
@property (strong,nonatomic) AVCaptureSession *captureSession;//负责输入和输出设备之间的数据传递
@property (strong,nonatomic) AVCaptureDeviceInput *captureDeviceInput;//负责从AVCaptureDevice获得输入数据
@property (strong,nonatomic) AVCaptureStillImageOutput *captureStillImageOutput;//照片输出流
@property (strong,nonatomic) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;//相机拍摄预览图层
@property (weak, nonatomic) IBOutlet UIView *viewContainer;
@property (weak, nonatomic) IBOutlet UIButton *takeButton;//拍照按钮
@property (weak, nonatomic) IBOutlet UIButton *flashAutoButton;//自动闪光灯按钮
@property (weak, nonatomic) IBOutlet UIButton *flashOnButton;//打开闪光灯按钮
@property (weak, nonatomic) IBOutlet UIButton *flashOffButton;//关闭闪光灯按钮
@property (weak, nonatomic) IBOutlet UIImageView *focusCursor; //聚焦光标
@end

在控制器视图将要展示时创建并初始化会话、摄像头设备、输入、输出、预览图层，并且添加预览图层到视图中，除此之外还做了一些初始化工作，例如添加手势（点击屏幕进行聚焦）、初始化界面等。

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    //初始化会话
    _captureSession=[[AVCaptureSession alloc]init];
    if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) {//设置分辨率
        _captureSession.sessionPreset=AVCaptureSessionPreset1280x720;
    }
    //获得输入设备
    AVCaptureDevice *captureDevice=[self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];//取得后置摄像头
    if (!captureDevice) {
        NSLog(@"取得后置摄像头时出现问题.");
        return;
    }
    
    NSError *error=nil;
    //根据输入设备初始化设备输入对象，用于获得输入数据
    _captureDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
    if (error) {
        NSLog(@"取得设备输入对象时出错，错误原因：%@",error.localizedDescription);
        return;
    }
    //初始化设备输出对象，用于获得输出数据
    _captureStillImageOutput=[[AVCaptureStillImageOutput alloc]init];
    NSDictionary *outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
    [_captureStillImageOutput setOutputSettings:outputSettings];//输出设置
    
    //将设备输入添加到会话中
    if ([_captureSession canAddInput:_captureDeviceInput]) {
        [_captureSession addInput:_captureDeviceInput];
    }
    
    //将设备输出添加到会话中
    if ([_captureSession canAddOutput:_captureStillImageOutput]) {
        [_captureSession addOutput:_captureStillImageOutput];
    }
    
    //创建视频预览层，用于实时展示摄像头状态
    _captureVideoPreviewLayer=[[AVCaptureVideoPreviewLayer alloc]initWithSession:self.captureSession];
    
    CALayer *layer=self.viewContainer.layer;
    layer.masksToBounds=YES;
    
    _captureVideoPreviewLayer.frame=layer.bounds;
    _captureVideoPreviewLayer.videoGravity=AVLayerVideoGravityResizeAspectFill;//填充模式
    //将视频预览层添加到界面中
    //[layer addSublayer:_captureVideoPreviewLayer];
    [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer];
    
    [self addNotificationToCaptureDevice:captureDevice];
    [self addGenstureRecognizer];
    [self setFlashModeButtonStatus];
}

在控制器视图展示和视图离开界面时启动、停止会话。

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    [self.captureSession startRunning];
}

-(void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    [self.captureSession stopRunning];
}

定义闪光灯开闭及自动模式功能，注意无论是设置闪光灯、白平衡还是其他输入设备属性，在设置之前必须先锁定配置，修改完后解锁。

/**
 *  改变设备属性的统一操作方法
 *
 *  @param propertyChange 属性改变操作
 */
-(void)changeDeviceProperty:(PropertyChangeBlock)propertyChange{
    AVCaptureDevice *captureDevice= [self.captureDeviceInput device];
    NSError *error;
    //注意改变设备属性前一定要首先调用lockForConfiguration:调用完之后使用unlockForConfiguration方法解锁
    if ([captureDevice lockForConfiguration:&error]) {
        propertyChange(captureDevice);
        [captureDevice unlockForConfiguration];
    }else{
        NSLog(@"设置设备属性过程发生错误，错误信息：%@",error.localizedDescription);
    }
}

/**
 *  设置闪光灯模式
 *
 *  @param flashMode 闪光灯模式
 */
-(void)setFlashMode:(AVCaptureFlashMode )flashMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFlashModeSupported:flashMode]) {
            [captureDevice setFlashMode:flashMode];
        }
    }];
}

定义切换摄像头功能，切换摄像头的过程就是将原有输入移除，在会话中添加新的输入，但是注意动态修改会话需要首先开启配置，配置成功后提交配置。

#pragma mark 切换前后摄像头
- (IBAction)toggleButtonClick:(UIButton *)sender {
    AVCaptureDevice *currentDevice=[self.captureDeviceInput device];
    AVCaptureDevicePosition currentPosition=[currentDevice position];
    [self removeNotificationFromCaptureDevice:currentDevice];
    AVCaptureDevice *toChangeDevice;
    AVCaptureDevicePosition toChangePosition=AVCaptureDevicePositionFront;
    if (currentPosition==AVCaptureDevicePositionUnspecified||currentPosition==AVCaptureDevicePositionFront) {
        toChangePosition=AVCaptureDevicePositionBack;
    }
    toChangeDevice=[self getCameraDeviceWithPosition:toChangePosition];
    [self addNotificationToCaptureDevice:toChangeDevice];
    //获得要调整的设备输入对象
    AVCaptureDeviceInput *toChangeDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil];
    
    //改变会话的配置前一定要先开启配置，配置完成后提交配置改变
    [self.captureSession beginConfiguration];
    //移除原有输入对象
    [self.captureSession removeInput:self.captureDeviceInput];
    //添加新的输入对象
    if ([self.captureSession canAddInput:toChangeDeviceInput]) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput=toChangeDeviceInput;
    }
    //提交会话配置
    [self.captureSession commitConfiguration];
    
    [self setFlashModeButtonStatus];
}

添加点击手势操作，点按预览视图时进行聚焦、白平衡设置。

/**
 *  设置聚焦点
 *
 *  @param point 聚焦点
 */
-(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        }
        if ([captureDevice isFocusPointOfInterestSupported]) {
            [captureDevice setFocusPointOfInterest:point];
        }
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        }
        if ([captureDevice isExposurePointOfInterestSupported]) {
            [captureDevice setExposurePointOfInterest:point];
        }
    }];
}

/**
 *  添加点按手势，点按时聚焦
 */
-(void)addGenstureRecognizer{
    UITapGestureRecognizer *tapGesture=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapScreen:)];
    [self.viewContainer addGestureRecognizer:tapGesture];
}
-(void)tapScreen:(UITapGestureRecognizer *)tapGesture{
    CGPoint point= [tapGesture locationInView:self.viewContainer];
    //将UI坐标转化为摄像头坐标
    CGPoint cameraPoint= [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point];
    [self setFocusCursorWithPoint:point];
    [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];
}

定义拍照功能，拍照的过程就是获取连接，从连接中获得捕获的输出数据并做保存操作。

#pragma mark 拍照
- (IBAction)takeButtonClick:(UIButton *)sender {
    //根据设备输出获得连接
    AVCaptureConnection *captureConnection=[self.captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo];
    //根据连接取得设备输出的数据
    [self.captureStillImageOutput captureStillImageAsynchronouslyFromConnection:captureConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        if (imageDataSampleBuffer) {
            NSData *imageData=[AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage *image=[UIImage imageWithData:imageData];
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
//            ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];
//            [assetsLibrary writeImageToSavedPhotosAlbum:[image CGImage] orientation:(ALAssetOrientation)[image imageOrientation] completionBlock:nil];
        }
        
    }];
}

最后附上完整代码：

//
//  ViewController.m
//  AVFoundationCamera
//
//  Created by Kenshin Cui on 14/04/05.
//  Copyright (c) 2014年 cmjstudio. All rights reserved.
//

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <AssetsLibrary/AssetsLibrary.h>
typedef void(^PropertyChangeBlock)(AVCaptureDevice *captureDevice);

@interface ViewController ()

@property (strong,nonatomic) AVCaptureSession *captureSession;//负责输入和输出设备之间的数据传递
@property (strong,nonatomic) AVCaptureDeviceInput *captureDeviceInput;//负责从AVCaptureDevice获得输入数据
@property (strong,nonatomic) AVCaptureStillImageOutput *captureStillImageOutput;//照片输出流
@property (strong,nonatomic) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;//相机拍摄预览图层
@property (weak, nonatomic) IBOutlet UIView *viewContainer;
@property (weak, nonatomic) IBOutlet UIButton *takeButton;//拍照按钮
@property (weak, nonatomic) IBOutlet UIButton *flashAutoButton;//自动闪光灯按钮
@property (weak, nonatomic) IBOutlet UIButton *flashOnButton;//打开闪光灯按钮
@property (weak, nonatomic) IBOutlet UIButton *flashOffButton;//关闭闪光灯按钮
@property (weak, nonatomic) IBOutlet UIImageView *focusCursor; //聚焦光标



@end

@implementation ViewController

#pragma mark - 控制器视图方法
- (void)viewDidLoad {
    [super viewDidLoad];
    
}

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    //初始化会话
    _captureSession=[[AVCaptureSession alloc]init];
    if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) {//设置分辨率
        _captureSession.sessionPreset=AVCaptureSessionPreset1280x720;
    }
    //获得输入设备
    AVCaptureDevice *captureDevice=[self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];//取得后置摄像头
    if (!captureDevice) {
        NSLog(@"取得后置摄像头时出现问题.");
        return;
    }
    
    NSError *error=nil;
    //根据输入设备初始化设备输入对象，用于获得输入数据
    _captureDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
    if (error) {
        NSLog(@"取得设备输入对象时出错，错误原因：%@",error.localizedDescription);
        return;
    }
    //初始化设备输出对象，用于获得输出数据
    _captureStillImageOutput=[[AVCaptureStillImageOutput alloc]init];
    NSDictionary *outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
    [_captureStillImageOutput setOutputSettings:outputSettings];//输出设置
    
    //将设备输入添加到会话中
    if ([_captureSession canAddInput:_captureDeviceInput]) {
        [_captureSession addInput:_captureDeviceInput];
    }
    
    //将设备输出添加到会话中
    if ([_captureSession canAddOutput:_captureStillImageOutput]) {
        [_captureSession addOutput:_captureStillImageOutput];
    }
    
    //创建视频预览层，用于实时展示摄像头状态
    _captureVideoPreviewLayer=[[AVCaptureVideoPreviewLayer alloc]initWithSession:self.captureSession];
    
    CALayer *layer=self.viewContainer.layer;
    layer.masksToBounds=YES;
    
    _captureVideoPreviewLayer.frame=layer.bounds;
    _captureVideoPreviewLayer.videoGravity=AVLayerVideoGravityResizeAspectFill;//填充模式
    //将视频预览层添加到界面中
    //[layer addSublayer:_captureVideoPreviewLayer];
    [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer];
    
    [self addNotificationToCaptureDevice:captureDevice];
    [self addGenstureRecognizer];
    [self setFlashModeButtonStatus];
}

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    [self.captureSession startRunning];
}

-(void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    [self.captureSession stopRunning];
}

-(void)dealloc{
    [self removeNotification];
}
#pragma mark - UI方法
#pragma mark 拍照
- (IBAction)takeButtonClick:(UIButton *)sender {
    //根据设备输出获得连接
    AVCaptureConnection *captureConnection=[self.captureStillImageOutput connectionWithMediaType:AVMediaTypeVideo];
    //根据连接取得设备输出的数据
    [self.captureStillImageOutput captureStillImageAsynchronouslyFromConnection:captureConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        if (imageDataSampleBuffer) {
            NSData *imageData=[AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage *image=[UIImage imageWithData:imageData];
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
            //            ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];
            //            [assetsLibrary writeImageToSavedPhotosAlbum:[image CGImage] orientation:(ALAssetOrientation)[image imageOrientation] completionBlock:nil];
        }
        
    }];
}
#pragma mark 切换前后摄像头
- (IBAction)toggleButtonClick:(UIButton *)sender {
    AVCaptureDevice *currentDevice=[self.captureDeviceInput device];
    AVCaptureDevicePosition currentPosition=[currentDevice position];
    [self removeNotificationFromCaptureDevice:currentDevice];
    AVCaptureDevice *toChangeDevice;
    AVCaptureDevicePosition toChangePosition=AVCaptureDevicePositionFront;
    if (currentPosition==AVCaptureDevicePositionUnspecified||currentPosition==AVCaptureDevicePositionFront) {
        toChangePosition=AVCaptureDevicePositionBack;
    }
    toChangeDevice=[self getCameraDeviceWithPosition:toChangePosition];
    [self addNotificationToCaptureDevice:toChangeDevice];
    //获得要调整的设备输入对象
    AVCaptureDeviceInput *toChangeDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil];
    
    //改变会话的配置前一定要先开启配置，配置完成后提交配置改变
    [self.captureSession beginConfiguration];
    //移除原有输入对象
    [self.captureSession removeInput:self.captureDeviceInput];
    //添加新的输入对象
    if ([self.captureSession canAddInput:toChangeDeviceInput]) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput=toChangeDeviceInput;
    }
    //提交会话配置
    [self.captureSession commitConfiguration];
    
    [self setFlashModeButtonStatus];
}

#pragma mark 自动闪光灯开启
- (IBAction)flashAutoClick:(UIButton *)sender {
    [self setFlashMode:AVCaptureFlashModeAuto];
    [self setFlashModeButtonStatus];
}
#pragma mark 打开闪光灯
- (IBAction)flashOnClick:(UIButton *)sender {
    [self setFlashMode:AVCaptureFlashModeOn];
    [self setFlashModeButtonStatus];
}
#pragma mark 关闭闪光灯
- (IBAction)flashOffClick:(UIButton *)sender {
    [self setFlashMode:AVCaptureFlashModeOff];
    [self setFlashModeButtonStatus];
}

#pragma mark - 通知
/**
 *  给输入设备添加通知
 */
-(void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice{
    //注意添加区域改变捕获通知必须首先设置设备允许捕获
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        captureDevice.subjectAreaChangeMonitoringEnabled=YES;
    }];
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //捕获区域发生改变
    [notificationCenter addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
-(void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice];
}
/**
 *  移除所有通知
 */
-(void)removeNotification{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    [notificationCenter removeObserver:self];
}

-(void)addNotificationToCaptureSession:(AVCaptureSession *)captureSession{
    NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter];
    //会话出错
    [notificationCenter addObserver:self selector:@selector(sessionRuntimeError:) name:AVCaptureSessionRuntimeErrorNotification object:captureSession];
}

/**
 *  设备连接成功
 *
 *  @param notification 通知对象
 */
-(void)deviceConnected:(NSNotification *)notification{
    NSLog(@"设备已连接...");
}
/**
 *  设备连接断开
 *
 *  @param notification 通知对象
 */
-(void)deviceDisconnected:(NSNotification *)notification{
    NSLog(@"设备已断开.");
}
/**
 *  捕获区域改变
 *
 *  @param notification 通知对象
 */
-(void)areaChange:(NSNotification *)notification{
    NSLog(@"捕获区域改变...");
}

/**
 *  会话出错
 *
 *  @param notification 通知对象
 */
-(void)sessionRuntimeError:(NSNotification *)notification{
    NSLog(@"会话发生错误.");
}

#pragma mark - 私有方法

/**
 *  取得指定位置的摄像头
 *
 *  @param position 摄像头位置
 *
 *  @return 摄像头设备
 */
-(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{
    NSArray *cameras= [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *camera in cameras) {
        if ([camera position]==position) {
            return camera;
        }
    }
    return nil;
}

/**
 *  改变设备属性的统一操作方法
 *
 *  @param propertyChange 属性改变操作
 */
-(void)changeDeviceProperty:(PropertyChangeBlock)propertyChange{
    AVCaptureDevice *captureDevice= [self.captureDeviceInput device];
    NSError *error;
    //注意改变设备属性前一定要首先调用lockForConfiguration:调用完之后使用unlockForConfiguration方法解锁
    if ([captureDevice lockForConfiguration:&error]) {
        propertyChange(captureDevice);
        [captureDevice unlockForConfiguration];
    }else{
        NSLog(@"设置设备属性过程发生错误，错误信息：%@",error.localizedDescription);
    }
}

/**
 *  设置闪光灯模式
 *
 *  @param flashMode 闪光灯模式
 */
-(void)setFlashMode:(AVCaptureFlashMode )flashMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFlashModeSupported:flashMode]) {
            [captureDevice setFlashMode:flashMode];
        }
    }];
}
/**
 *  设置聚焦模式
 *
 *  @param focusMode 聚焦模式
 */
-(void)setFocusMode:(AVCaptureFocusMode )focusMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:focusMode];
        }
    }];
}
/**
 *  设置曝光模式
 *
 *  @param exposureMode 曝光模式
 */
-(void)setExposureMode:(AVCaptureExposureMode)exposureMode{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:exposureMode];
        }
    }];
}
/**
 *  设置聚焦点
 *
 *  @param point 聚焦点
 */
-(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isFocusModeSupported:focusMode]) {
            [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        }
        if ([captureDevice isFocusPointOfInterestSupported]) {
            [captureDevice setFocusPointOfInterest:point];
        }
        if ([captureDevice isExposureModeSupported:exposureMode]) {
            [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        }
        if ([captureDevice isExposurePointOfInterestSupported]) {
            [captureDevice setExposurePointOfInterest:point];
        }
    }];
}

/**
 *  添加点按手势，点按时聚焦
 */
-(void)addGenstureRecognizer{
    UITapGestureRecognizer *tapGesture=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapScreen:)];
    [self.viewContainer addGestureRecognizer:tapGesture];
}
-(void)tapScreen:(UITapGestureRecognizer *)tapGesture{
    CGPoint point= [tapGesture locationInView:self.viewContainer];
    //将UI坐标转化为摄像头坐标
    CGPoint cameraPoint= [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point];
    [self setFocusCursorWithPoint:point];
    [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];
}

/**
 *  设置闪光灯按钮状态
 */
-(void)setFlashModeButtonStatus{
    AVCaptureDevice *captureDevice=[self.captureDeviceInput device];
    AVCaptureFlashMode flashMode=captureDevice.flashMode;
    if([captureDevice isFlashAvailable]){
        self.flashAutoButton.hidden=NO;
        self.flashOnButton.hidden=NO;
        self.flashOffButton.hidden=NO;
        self.flashAutoButton.enabled=YES;
        self.flashOnButton.enabled=YES;
        self.flashOffButton.enabled=YES;
        switch (flashMode) {
            case AVCaptureFlashModeAuto:
                self.flashAutoButton.enabled=NO;
                break;
            case AVCaptureFlashModeOn:
                self.flashOnButton.enabled=NO;
                break;
            case AVCaptureFlashModeOff:
                self.flashOffButton.enabled=NO;
                break;
            default:
                break;
        }
    }else{
        self.flashAutoButton.hidden=YES;
        self.flashOnButton.hidden=YES;
        self.flashOffButton.hidden=YES;
    }
}

/**
 *  设置聚焦光标位置
 *
 *  @param point 光标位置
 */
-(void)setFocusCursorWithPoint:(CGPoint)point{
    self.focusCursor.center=point;
    self.focusCursor.transform=CGAffineTransformMakeScale(1.5, 1.5);
    self.focusCursor.alpha=1.0;
    [UIView animateWithDuration:1.0 animations:^{
        self.focusCursor.transform=CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        self.focusCursor.alpha=0;
        
    }];
}
@end
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