iOS：从前置摄像头捕获图像

发展注意事项：

>仔细检查你的应用程序和图像方向设置
> AVFoundation及其相关框架是讨厌的巨兽,非常难以理解/实施.我使我的代码尽可能精简,但请查看这个优秀的教程,以获得更好的解释(网站不再提供,通过archive.org链接)：
http://www.benjaminloulier.com/posts/ios4-and-direct-access-to-the-camera

ViewController.h

// Frameworks
#import <CoreVideo/CoreVideo.h>
#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>
#import <UIKit/UIKit.h>

@interface CameraviewController : UIViewController <AVCaptureVideoDataOutputSampleBufferDelegate>

// Camera
@property (weak,nonatomic) IBOutlet UIImageView* cameraimageView;
@property (strong,nonatomic) AVCaptureDevice* device;
@property (strong,nonatomic) AVCaptureSession* captureSession;
@property (strong,nonatomic) AVCaptureVideoPreviewLayer* previewLayer;
@property (strong,nonatomic) UIImage* cameraimage;

@end

ViewController.m

#import "CameraviewController.h"

@implementation CameraviewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self setupCamera];
    [self setupTimer];
}

- (void)setupCamera
{    
    NSArray* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for(AVCaptureDevice *device in devices)
    {
        if([device position] == AVCaptureDevicePositionFront)
            self.device = device;
    }

    AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
    AVCaptureVideoDataOutput* output = [[AVCaptureVideoDataOutput alloc] init];
    output.alwaysdiscardsLateVideoFrames = YES;

    dispatch_queue_t queue;
    queue = dispatch_queue_create("cameraQueue",NULL);
    [output setSampleBufferDelegate:self queue:queue];

    Nsstring* key = (Nsstring *) kCVPixelBufferPixelFormatTypeKey;
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
    [output setVideoSettings:videoSettings];

    self.captureSession = [[AVCaptureSession alloc] init];
    [self.captureSession addInput:input];
    [self.captureSession addOutput:output];
    [self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];

    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

    // CHECK FOR YOUR APP
    self.previewLayer.frame = CGRectMake(0,self.view.frame.size.height,self.view.frame.size.width);
    self.previewLayer.orientation = AVCaptureVideoOrientationLandscapeRight;
    // CHECK FOR YOUR APP

    [self.view.layer insertSublayer:self.previewLayer atIndex:0];   // Comment-out to hide preview layer

    [self.captureSession startRunning];
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetimageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer,0);
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef newContext = CGBitmapContextCreate(baseAddress,width,height,8,bytesPerRow,colorSpace,kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef newImage = CGBitmapContextCreateImage(newContext);

    CGContextRelease(newContext);
    CGColorSpaceRelease(colorSpace);

    self.cameraimage = [UIImage imageWithCGImage:newImage scale:1.0f orientation:UIImageOrientationDownMirrored];

    CGImageRelease(newImage);

    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}

- (void)setupTimer
{
    NSTimer* cameraTimer = [NSTimer scheduledTimerWithTimeInterval:2.0f target:self selector:@selector(snapshot) userInfo:nil repeats:YES];
}

- (void)snapshot
{
    NSLog(@"SNAPSHOT");
    self.cameraimageView.image = self.cameraimage;  // Comment-out to hide snapshot
}

@end

将其连接到具有UIImageView的UIViewController用于快照,它将工作！快照以2.0秒的间隔以编程方式进行,无任何用户输入.注释所选行以删除预览图层和快照反馈.

任何更多的问题/意见,请让我知道！