Resize UIImage to generate thumbnail in apple iOS app - Xcode.

+ (UIImage *)generatePhotoThumbnail:(UIImage *)image withSide:(CGFloat)ratio

{

// Create a thumbnail version of the image for the event object.

CGSize size = image.size;

CGSize croppedSize;

CGFloat offsetX = 0.0;

CGFloat offsetY = 0.0;

    

// check the size of the image, we want to make it

// a square with sides the size of the smallest dimension.

    // So clip the extra portion from x or y coordinate

if (size.width > size.height) {

offsetX = (size.height - size.width) / 2;

croppedSize = CGSizeMake(size.height, size.height);

} else {

offsetY = (size.width - size.height) / 2;

croppedSize = CGSizeMake(size.width, size.width);

}

    

// Crop the image before resize

CGRect clippedRect = CGRectMake(offsetX * -1, offsetY * -1, croppedSize.width, croppedSize.height);

CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);

// Done cropping

    

// Resize the image

CGRect rect = CGRectMake(0.0, 0.0, ratio, ratio);

    

UIGraphicsBeginImageContext(rect.size);

[[UIImage imageWithCGImage:imageRef] drawInRect:rect];

UIImage *thumbnail = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

// Done Resizing

    

return thumbnail;

}