通过代码获得每一帧的图片（iOS）

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <NYXImagesKit.h>
@interface ViewController ()<AVCaptureVideoDataOutputSampleBufferDelegate>
{
    AVCaptureSession *_session;
    NSMutableArray *_imageArr;
    UIScrollView *_scrollView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    _imageArr = [[NSMutableArray alloc] init];
    _session = [[AVCaptureSession alloc] init];
    _session.sessionPreset = AVCaptureSessionPresetPhoto;
    AVCaptureVideoPreviewLayer *layer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_session];
    layer.frame = [UIScreen mainScreen].bounds;
    layer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:layer];
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
//    device.focusMode = AVCaptureFocusModeContinuousAutoFocus;
//    [device unlockForConfiguration];
    AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc] initWithDevice:device error:nil];
    AVCaptureStillImageOutput *output = [[AVCaptureStillImageOutput alloc] init];
    
    dispatch_queue_t captureQueue = dispatch_queue_create("com.kai.captureQueue", NULL);
    AVCaptureVideoDataOutput *output2 = [[AVCaptureVideoDataOutput alloc] init];
    output2.videoSettings = @{(NSString*)kCVPixelBufferPixelFormatTypeKey: [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]};
    output2.alwaysDiscardsLateVideoFrames = YES;
    [output2 setSampleBufferDelegate:self queue:captureQueue];
    if ([_session canAddInput:input]){
        [_session addInput:input];
    }
    if ([_session canAddOutput:output]) {
        [_session addOutput:output];
        [_session addOutput:output2];
    }
    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    [button setTitle:@"开启" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(onClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
    button.bounds = CGRectMake(0, 0, 100, 40);
    button.center = self.view.center;
    UIButton *button2 = [UIButton buttonWithType:UIButtonTypeSystem];
    [button2 setTitle:@"关闭" forState:UIControlStateNormal];
    [button2 addTarget:self action:@selector(onClick01) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button2];
    button2.bounds = CGRectMake(0, 0, 100, 40);
    button2.center = CGPointMake(self.view.center.x, self.view.center.y+100);
    _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height/2-30)];
    _scrollView.backgroundColor = [UIColor redColor];
    _scrollView.alwaysBounceHorizontal = YES;
    _scrollView.contentSize = CGSizeZero;
    _scrollView.pagingEnabled = YES;
    [self.view addSubview:_scrollView];
}

- (void)onClick{
    [_session startRunning];
}

- (void)onClick01{
    [_session stopRunning];
    for (int i = 0 ; i<_imageArr.count; i++) {
        UIImage *image = _imageArr[i];
        UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
        imageView.contentMode = UIViewContentModeScaleAspectFit;
        imageView.frame = CGRectMake(self.view.frame.size.width*i, 0, self.view.frame.size.width,_scrollView.frame.size.height);
        [_scrollView addSubview:imageView];
        _scrollView.contentSize = CGSizeMake(image.size.width*i, 0);
    }
    

}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    CGRect rect = CGRectMake(0, 0, CVPixelBufferGetWidth(pixelBuffer), CVPixelBufferGetHeight(pixelBuffer));
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef imageRef = [context createCGImage:ciImage fromRect:rect];
    UIImage *image = [UIImage imageWithCGImage:imageRef];
    image = [image rotateInDegrees:90.0f];
    [_imageArr addObject:image];
    CGImageRelease(imageRef);
}




- (void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    [_session stopRunning];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end