How to capture image with AVFoundation framework?

问题

I have following code to open the camera in UIView ,that is working right now.

But i have two buttons like in this screen shot one for capturing photo and another one for upload photo from library.

How do i capture photo without going to native camera ?

Here is my .h file code

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface bgCameraController : UIViewController<AVCaptureMetadataOutputObjectsDelegate>

@property (weak, nonatomic) IBOutlet UIView *cam;
@property (strong, nonatomic) IBOutlet UIImageView *imageView;

- (IBAction)takePhoto:  (UIButton *)sender;
- (IBAction)selectPhoto:(UIButton *)sender;
@end

Here is my .m file code

#import "bgCameraController.h"

@interface bgCameraController ()
@property (nonatomic, strong) AVCaptureSession *captureSession;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
@property (nonatomic) BOOL isReading;

-(BOOL)startReading;
-(void)stopReading;
-(void)loadBeepSound;
@end

@implementation bgCameraController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadBeepSound];
    [self startReading];

    // Do any additional setup after loading the view.
}

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

- (BOOL)startReading {
    NSError *error;

    // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video
    // as the media type parameter.
    AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    // Get an instance of the AVCaptureDeviceInput class using the previous device object.
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

    if (!input) {
        // If any error occurs, simply log the description of it and don't continue any more.
        NSLog(@"%@", [error localizedDescription]);
        return NO;
    }

    // Initialize the captureSession object.
    _captureSession = [[AVCaptureSession alloc] init];
    // Set the input device on the capture session.
    [_captureSession addInput:input];


    // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
    AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    [_captureSession addOutput:captureMetadataOutput];

    // Create a new serial dispatch queue.
    dispatch_queue_t dispatchQueue;
    dispatchQueue = dispatch_queue_create("myQueue", NULL);
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
    [captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
    [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [_videoPreviewLayer setFrame:_cam.layer.bounds];
    [_cam.layer addSublayer:_videoPreviewLayer];


    // Start video capture.
    [_captureSession startRunning];

    return YES;
}


-(void)stopReading{
    // Stop video capture and make the capture session object nil.
    [_captureSession stopRunning];
    _captureSession = nil;

    // Remove the video preview layer from the viewPreview view's layer.
    //[_videoPreviewLayer removeFromSuperlayer];
}


-(void)loadBeepSound{
    // Get the path to the beep.mp3 file and convert it to a NSURL object.
    NSString *beepFilePath = [[NSBundle mainBundle] pathForResource:@"beep" ofType:@"mp3"];
    NSURL *beepURL = [NSURL URLWithString:beepFilePath];

    NSError *error;

    // Initialize the audio player object using the NSURL object previously set.
    _audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:beepURL error:&error];
    if (error) {
        // If the audio player cannot be initialized then log a message.
        // NSLog(@"Could not play beep file.");
        //NSLog(@"%@", [error localizedDescription]);
    }
    else{
        // If the audio player was successfully initialized then load it in memory.
        [_audioPlayer prepareToPlay];
    }
}
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{

    // Check if the metadataObjects array is not nil and it contains at least one object.
    if (metadataObjects != nil && [metadataObjects count] > 0) {
        // Get the metadata object.
        // NSLog(@"%@",metadataObjects);
        AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
        if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {
            // If the found metadata is equal to the QR code metadata then update the status label's text,
            // stop reading and change the bar button item's title and the flag's value.
            // Everything is done on the main thread.
            NSString *result=[metadataObj stringValue];
            [self performSelectorOnMainThread:@selector(setQRcodeValues:) withObject:result waitUntilDone:NO];
            //  [_result performSelectorOnMainThread:@selector(setText:) withObject:[metadataObj stringValue] waitUntilDone:NO];

            [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];
            // [_button performSelectorOnMainThread:@selector(setTitle:) withObject:@"Start!" waitUntilDone:NO];

            _isReading = NO;

            // If the audio player is not nil, then play the sound effect.
            if (_audioPlayer) {
                [_audioPlayer play];
            }
        }
    }


}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

Please help me... to capture photo by clicking that button (check the link image)

回答1:

I have captured image while scanning QRCode like this:

1) Firstly add property of AVCaptureStillImageOutput's

@property (strong, nonatomic) AVCaptureStillImageOutput *stillImageOutput;

2) Add session preset in AVCaptureSession after initializing it

[self.session setSessionPreset:AVCaptureSessionPreset640x480];

3) Now add AVCaptureStillImageOutput's as output in AVCaptureSession

// Prepare an output for snapshotting
self.stillImageOutput = [AVCaptureStillImageOutput new];
[self.session addOutput:self.stillImageOutput];
self.stillImageOutput.outputSettings = @{AVVideoCodecKey: AVVideoCodecJPEG};

4) Make add below code to capture scanned image in delegate method captureOutput:didOutputMetadataObjects:fromConnection:connection

 __block UIImage *scannedImg = nil;
// Take an image of the face and pass to CoreImage for detection
AVCaptureConnection *stillConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:stillConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
    if(error) {
        NSLog(@"There was a problem");
        return;
    }

    NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];

    scannedImg = [UIImage imageWithData:jpegData];
    NSLog(@"scannedImg : %@",scannedImg);
}];

For reference use CodeScanViewController

Thats it @Enjoy

来源：https://stackoverflow.com/questions/26382254/how-to-capture-image-with-avfoundation-framework