get thumbnail from UIImagePickerController when using CAMERA (not album) - ios

Question

It's very easy to get a thumbnail when using the ALBUM with UIImagePickerController.
It's even easy to get a thumbnail from a VIDEO.
But when you're using the CAMERA,
self.cameraController.sourceType = UIImagePickerControllerSourceTypeCamera;
and you come back to
-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
How do you quickly get a thumbnail?
Note, I'm not particularly trying to SAVE the image .. I want to use the image from the camera (imagine then using it in a drawing screen, or for image processing, etc.)
Below, a naive category that turns the image in to a 128.128 image. But it's way too slow.
Many apps move very quickly from the camera, to the next screen (say, editing the image or drawing on it). What's the technique? Cheers
-(UIImage *)squareAndSmall
{
// this category works fine to make a 128.128 thumbnail,
// but it is very slow
CGSize finalsize = CGSizeMake(128,128);
CGFloat scale = MAX(
finalsize.width/self.size.width,
finalsize.height/self.size.height);
CGFloat width = self.size.width * scale;
CGFloat height = self.size.height * scale;
//uses the central area, say....
CGRect imageRect = CGRectMake(
(finalsize.width - width)/2.0f,
(finalsize.height - height)/2.0f,
width, height);
UIGraphicsBeginImageContextWithOptions(finalsize, NO, 0);
[self drawInRect:imageRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Answer 1

Try using "AssetLibrary.framework" to write the image to your camera roll and it will automatically create a thumbnail representation for you. Moreover, as this process is asynchronous, it will certainly be a performance boost for the app.
Try some thing like the following:
#import <AssetsLibrary/AssetsLibrary.h>
////.........your code
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
/////.........
UIImage* img = info[UIImagePickerControllerOriginalImage];
ALAssetsLibrary *library = [ALAssetsLibrary new];
[library writeImageToSavedPhotosAlbum:[img CGImage] orientation:(ALAssetOrientation)[img imageOrientation] completionBlock:^(NSURL *assetURL, NSError *error){
if (error) {
NSLog(#"error");
return;
}
[library assetForURL:assetURL resultBlock:^(ALAsset *asset) {
[self.imageViewer setImage:[UIImage imageWithCGImage:[asset aspectRatioThumbnail]]]; //self.imageViewer is a UIImageView to display thumbnail
} failureBlock:^(NSError *error) {
NSLog(#"Failed to load captured image.");
}];
}];
[library release];
//................
}
////......rest of your code
I have not tested the code but I hope, it should fulfill your purpose. Please make sure to add a reference of "AssetLibrary.framework" to your project before you try and let me know if it worked out for you.