首先通過(guò)#import <AVFoundation/AVFoundation.h> 捕捉手機(jī)屏幕圖像住涉。
主要代碼：

@interface ViewController ()<AVCaptureVideoDataOutputSampleBufferDelegate>
//硬件設(shè)備
@property (nonatomic, strong) AVCaptureDevice *device;
//輸入流
@property (nonatomic, strong) AVCaptureDeviceInput *input;
//協(xié)調(diào)輸入輸出流的數(shù)據(jù)
@property (nonatomic, strong) AVCaptureSession *session;
//預(yù)覽層
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
//輸出流
@property (nonatomic, strong) AVCaptureVideoDataOutput *videoDataOutput;

@end

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view.layer addSublayer:self.previewLayer];
    [self.session startRunning];
}
#pragma mark - AVCaptureVideoDataOutputSampleBufferDelegate
//AVCaptureVideoDataOutput獲取實(shí)時(shí)圖像俄占，這個(gè)代理方法的回調(diào)頻率很快腔长，幾乎與手機(jī)屏幕的刷新頻率一樣快
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
    //設(shè)置圖像方向辐烂，否則largeImage取出來(lái)是反的
    [connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
    //獲取圖像圖片（使用下面人臉捕捉代碼即可）   
 largeImage = [self imageFromSampleBuffer:sampleBuffer];
}

//CMSampleBufferRef轉(zhuǎn)NSImage
-(UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer{
    // 為媒體數(shù)據(jù)設(shè)置一個(gè)CMSampleBuffer的Core Video圖像緩存對(duì)象
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    // 鎖定pixel buffer的基地址
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    // 得到pixel buffer的基地址
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
    // 得到pixel buffer的行字節(jié)數(shù)
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    // 得到pixel buffer的寬和高
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    // 創(chuàng)建一個(gè)依賴于設(shè)備的RGB顏色空間
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    // 用抽樣緩存的數(shù)據(jù)創(chuàng)建一個(gè)位圖格式的圖形上下文（graphics context）對(duì)象
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    // 根據(jù)這個(gè)位圖context中的像素?cái)?shù)據(jù)創(chuàng)建一個(gè)Quartz image對(duì)象
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    // 解鎖pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
    // 釋放context和顏色空間
    CGContextRelease(context); CGColorSpaceRelease(colorSpace);
    // 用Quartz image創(chuàng)建一個(gè)UIImage對(duì)象image
    UIImage *image = [UIImage imageWithCGImage:quartzImage];
    // 釋放Quartz image對(duì)象
    CGImageRelease(quartzImage);
    return (image);
}


-(AVCaptureDeviceInput *)input{
    if (_input == nil) {
        _input = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:nil];
    }
    return _input;
}


-(AVCaptureVideoDataOutput *)videoDataOutput{
    if (_videoDataOutput == nil) {
        _videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
        [_videoDataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
        //設(shè)置像素格式遏插，否則CMSampleBufferRef轉(zhuǎn)換NSImage的時(shí)候CGContextRef初始化會(huì)出問(wèn)題
        [_videoDataOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];
    }
    return _videoDataOutput;
}

-(AVCaptureSession *)session{
    if (_session == nil) {
        _session = [[AVCaptureSession alloc] init];
        if ([_session canAddInput:self.input]) {
            [_session addInput:self.input];
        }
        if ([_session canAddOutput:self.videoDataOutput]) {
            [_session addOutput:self.videoDataOutput];
        }
    }
    return _session;
}

-(AVCaptureVideoPreviewLayer *)previewLayer{
    if (_previewLayer == nil) {
        _previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
        _previewLayer.frame = self.view.layer.bounds;
    }
    return _previewLayer;
}

主要使用#import <CoreImage/CoreImage.h>框架捕捉，簡(jiǎn)單代碼如下

// 圖像識(shí)別能力：可以在CIDetectorAccuracyHigh(較強(qiáng)的處理能力)與CIDetectorAccuracyLow(較弱的處理能力)中選擇纠修，因?yàn)橄胱寽?zhǔn)確度高一些在這里選擇CIDetectorAccuracyHigh
    NSDictionary *opts = [NSDictionary dictionaryWithObject:
                          CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];
    // 將圖像轉(zhuǎn)換為CIImage
    CIImage *faceImage = [CIImage imageWithCGImage:image.CGImage];
    CIDetector *faceDetector=[CIDetector detectorOfType:CIDetectorTypeFace context:nil options:opts];
    // 識(shí)別出人臉數(shù)組
    NSArray *features = [faceDetector featuresInImage:faceImage options: [NSDictionary dictionaryWithObject:@(5) forKey:CIDetectorImageOrientation]];

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