Resize Image to certain size while retaining aspect ratio, crop image if necessary (iOS)

Question

I'm using UIImagePickerController to choose an image from my Camera Roll and resizing it before uploading it to Parse.

I want to resize an image to certain size (let's say 750x1000) while retaining the aspect ratio of the original image. If necessary, I want to crop the image. I also want it to be easy to have different versions of the image (full size, thumbnail size). Right now I'm resizing only the height of the image. How can I achieve what I'm looking for?

Thanks.

NewProductViewController.h

@interface NewProductViewController : UIViewController <UINavigationControllerDelegate, UIImagePickerControllerDelegate, UITextFieldDelegate>

@property (nonatomic, strong) UIImage *image;
@property (nonatomic, strong) UIImagePickerController *imagePicker;
@property (nonatomic, weak) IBOutlet UIImageView *imageView;

- (UIImage *)imageWithImage:(UIImage *)sourceImage scaledToHeight:(float) i_height;

@end

NewProductViewController.m

- (IBAction)addImage:(id)sender {
    self.imagePicker = [[UIImagePickerController alloc] init];
    self.imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    self.imagePicker.delegate = self;
    self.imagePicker.allowsEditing = NO;

    [self presentViewController:self.imagePicker animated:NO completion:nil];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];

    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
        // A photo was selected
        self.image = [info objectForKey:UIImagePickerControllerOriginalImage];
        if (self.imagePicker.sourceType == UIImagePickerControllerSourceTypeCamera) {
            // Save the image!
            UIImageWriteToSavedPhotosAlbum(self.image, nil, nil, nil);
        }
    }

    [self.imageView setImage:self.image];

    [self dismissViewControllerAnimated:YES completion:nil];
}
- (UIImage *)imageWithImage:(UIImage *)sourceImage scaledToHeight:(float) i_height {
    float oldHeight = sourceImage.size.height;
    float scaleFactor = i_height / oldHeight;

    float newWidth = sourceImage.size.width* scaleFactor;
    float newHeight = oldHeight * scaleFactor;

    UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
    [sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

- (IBAction)createProduct:(id)sender {
    PFObject *newProduct = [PFObject objectWithClassName:@"Product"];

    UIImage *newImage = [self imageWithImage:self.image scaledToHeight:1000.f];
    UIImage *thumbnailImage = [self imageWithImage:self.image scaledToHeight:410.f];

    NSData *imageData = UIImageJPEGRepresentation(newImage, 0.8f);
    NSData *thumbnailData = UIImageJPEGRepresentation(thumbnailImage, 0.8f);

    PFFile *imageFile = [PFFile fileWithName:@"image.jpg" data:imageData];
    PFFile *thumbnailFile = [PFFile fileWithName:@"thumbnail.jpg" data:thumbnailData];

    newProduct[@"imageFile"] = imageFile;
    newProduct[@"thumbnailFile"] = thumbnailFile;

    [newProduct setObject:[PFUser currentUser] forKey:@"user"];
}

Answer 1

Try this one, it crops source image proportionally and then scales it to necessary size:

- (UIImage *)imageWithImage:(UIImage *)sourceImage size:(CGSize)size {
    CGSize newSize = CGSizeZero;
    if ((sourceImage.size.width / size.width) < (sourceImage.size.height / size.height)) {
        newSize = CGSizeMake(sourceImage.size.width, size.height * (sourceImage.size.width / size.width));
    } else {
        newSize = CGSizeMake(size.width * (sourceImage.size.height / size.height), sourceImage.size.height);
    }

    CGRect cropRect = CGRectZero;
    cropRect.origin.x = (sourceImage.size.width - newSize.width) / 2.0f;
    cropRect.origin.y = (sourceImage.size.height - newSize.height) / 2.0f;
    cropRect.size = newSize;

    CGImageRef croppedImageRef = CGImageCreateWithImageInRect([sourceImage CGImage], cropRect);
    UIImage *croppedImage = [UIImage imageWithCGImage:croppedImageRef];
    CGImageRelease(croppedImageRef);

    UIGraphicsBeginImageContextWithOptions(CGSizeMake(size.width, size.height), NO, 0.0);
    [croppedImage drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return scaledImage;
}

Answer 2

This code can help you:

UIImage *originalImage = [UIImage imageNamed:@"minions.png"];
CGSize destination = CGSizeMake(750, 1000);
UIGraphicsBeginImageContext(destination);
[originalImage drawInRect:CGRectMake(0,0,destination.width,destination.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *new = [[UIImageView alloc] initWithFrame:CGRectMake(40, 40, 750, 1000)];
new.image = newImage;
[self.view addSubview:New];

Let me know if it works for you :)