關(guān)于AVFoundation介紹"http://www.reibang.com/p/8c5c150dba65"

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導(dǎo)入頭文件

#import <AVFoundation/AVFoundation.h>

遵循代理協(xié)議

<AVCaptureMetadataOutputObjectsDelegate>

//捕捉會話
@property(nonatomic,strong)AVCaptureSession *captureSession;
//展示layer
@property (nonatomic,strong)AVCaptureVideoPreviewLayer *videoPreviewLayer;
//保存屏幕中離開的人臉
@property(nonatomic,strong)NSMutableArray *leaveFaceArray;
//保存屏幕檢測到臉對應(yīng)的layer faceID 作為字典 key
@property(nonatomic,strong)NSMutableDictionary *faceLayerDic;

-(NSMutableDictionary *)faceLayerDic{
    if (!_faceLayerDic) {
        
        _faceLayerDic = [NSMutableDictionary dictionaryWithCapacity:10];
    }
    
    return _faceLayerDic;
}

-(void)viewWillAppear:(BOOL)animated{
    
    [super viewWillAppear:animated];
    
     [self startReading];
    
}

檢測攝像頭數(shù)量

- (NSUInteger)cameraCounts {
    
    return [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
}

獲取前置攝像頭

- (AVCaptureDevice *)inactiveCamera {
    AVCaptureDevice *deviceSelect = nil;
    if (self.cameraCounts > 1) {
        
        NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        for (AVCaptureDevice *device in devices) {
            if (device.position == AVCaptureDevicePositionFront) {
               
                deviceSelect = device;
            }
        }
    }
    
    return deviceSelect;
}

開始識別

-(void)startReading{
    
    //讀取攝像頭授權(quán)狀態(tài)
    NSString *mediaType = AVMediaTypeVideo;//讀取媒體類型
    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];//讀取設(shè)備授權(quán)狀態(tài)
    if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied){
     
        // 提示開啟權(quán)限
        
        return;
    }
  
    NSError *error;
    
    //1.初始化捕捉設(shè)備（AVCaptureDevice）害幅，類型為AVMediaTypeVideo
    AVCaptureDevice *captureDevice = [self inactiveCamera];

    
    //2.用captureDevice創(chuàng)建輸入流,輸入設(shè)備轉(zhuǎn)換成AVCaptureDeviceInput對象
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];
    
    if (!input) {
        NSLog(@"%@", [error localizedDescription]);
      
        return ;
    }
    //3.創(chuàng)建媒體數(shù)據(jù)輸出流
    AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    
    //4.實例化捕捉會話
    self.captureSession = [[AVCaptureSession alloc] init];
    
    self.captureSession.sessionPreset = AVCaptureSessionPresetHigh;
    
    //4.1.將輸入設(shè)備添加到會話
    if ([self.captureSession canAddInput:input]) {

        [self.captureSession addInput:input];
    }
    //4.2.將媒體輸出設(shè)備添加到會話
    if ([self.captureSession canAddOutput:captureMetadataOutput]) {
        
        [self.captureSession addOutput:captureMetadataOutput];
        
    }
    
    NSArray *metaDataObjectTypes = @[AVMetadataObjectTypeFace];
    //4.3.攝像頭在捕捉數(shù)據(jù)時,只會對人臉元數(shù)據(jù)感興趣
    captureMetadataOutput.metadataObjectTypes = metaDataObjectTypes;
   
    //獲得主隊列,因為人臉檢測用到硬件加速,而且很多任務(wù)都在主線程執(zhí)行
    dispatch_queue_t mainQueue = dispatch_get_main_queue();
    
    //設(shè)置代理 主隊列
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:mainQueue];
    
    
    //5.實例化預(yù)覽圖層
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
    
    //6.設(shè)置預(yù)覽圖層填充方式
    [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    
    //7.設(shè)置圖層的frame
    [_videoPreviewLayer setFrame:self.view.bounds];
    
    [UIView animateWithDuration:2 animations:^{
        
        [self.view.layer addSublayer:_videoPreviewLayer];
        
    }];
    
    //開啟會話
    [self.captureSession startRunning];
 
}

代理方法 獲取捕獲的數(shù)據(jù)

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputMetadataObjects:(NSArray *)metadataObjects
       fromConnection:(AVCaptureConnection *)connection {
    
  NSMutableArray *faceArray = [NSMutableArray arrayWithCapacity:10];
    
    //獲取的人臉放到數(shù)組中
    
    for (AVMetadataFaceObject *face in metadataObjects) {
        
    //NSLog(@"faceID:%li",(long)face.faceID);
   // NSLog(@"face.bounds:%@",NSStringFromCGRect(face.bounds));
        
        //將攝像頭捕捉的人臉位置轉(zhuǎn)換到屏幕位置
        AVMetadataObject *tranformFace = [_videoPreviewLayer  transformedMetadataObjectForMetadataObject:face];
        
        [faceArray addObject:tranformFace];
    }

    //將獲取的人臉數(shù)據(jù)進(jìn)行處理
    [self faceOperation:faceArray];

}

-(void)faceOperation:(NSArray *)faceArray{
    
   NSMutableArray *leaveFaceArray = [self.faceLayerDic.allKeys mutableCopy];
    
    for (AVMetadataFaceObject *face in faceArray) {
     
        NSNumber *faceID = @(face.faceID);
        [leaveFaceArray removeObject:faceID];
        CALayer *layer = self.faceLayerDic[faceID];
     
        if(!layer){
           
          //makeFacelayer :新建一個人臉圖層
            layer = [self makeFaceLayer];
        
            //將人臉圖層添加到videoPreviewLayer
         
            [self.videoPreviewLayer addSublayer:layer];
            
            //將 layer加入字典中
            self.faceLayerDic[faceID] = layer;
        }
        //指定圖層的位置
        layer.frame = face.bounds;
    
    }
  
    for (NSNumber *faceID in leaveFaceArray) { 
        CALayer *layer = self.faceLayerDic[faceID];
        [layer removeFromSuperlayer];
        [self.faceLayerDic removeObjectForKey:faceID];
        
    }
}

- (CALayer *)makeFaceLayer {
    CALayer *layer = [CALayer layer];
    layer.borderWidth = 2.0f;
    layer.borderColor = [UIColor redColor].CGColor;
    return layer;
}