How to take square picture in iphone with avFoundation like in Instagram app?

Question

I am taking photo with AVFoundation like here: http://red-glasses.com/index.php/tutorials/ios4-take-photos-with-live-video-preview-using-avfoundation/

One snippet:

[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
 {
     CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);
     if (exifAttachments)
     {
         // Do something with the attachments.
         NSLog(@"attachements: %@", exifAttachments);
     }
     else
         NSLog(@"no attachments");

     NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
     UIImage *image = [[UIImage alloc] initWithData:imageData];

Picture size as far as i found out is set here:

   AVCaptureSession *session = [[AVCaptureSession alloc] init];  
   session.sessionPreset =AVCaptureSessionPresetMedium; //medium on my iphone4 is 640*480

But here are only few settings possible and cant be set to custom size.

I would like taken pictures to have aspect ratio 1:1 if possible, for example 400x400 pixels (square pictures). It seems instagram is doing it (or are they cropping images?).

How can i specify the size of taken picture to be square? I know how to change size on the phone, but if the taken picture is not square, the result is not good.

Any idea?

Answer 1

You should probably be resizing your UIImage by creating a new context. Examples below

.....
UIImage *image = [[UIImage alloc] initWithData:imageData];
UIImage *tempImage = nil;
CGSize targetSize = CGSizeMake(400,400);
UIGraphicsBeginImageContext(targetSize);

CGRect thumbnailRect = CGRectMake(0, 0, 0, 0);
thumbnailRect.origin = CGPointMake(0.0,0.0);
thumbnailRect.size.width  = targetSize.width;
thumbnailRect.size.height = targetSize.height;

[image drawInRect:thumbnailRect];

tempImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

// tmpImage is resized to 400x400

Hope this helps !