Resize Uiimage With Aspect Ratio

Resize UIImage by keeping Aspect ratio and width

The method of Srikar works very well, if you know both height and width of your new Size.
If you for example know only the width you want to scale to and don't care about the height you first have to calculate the scale factor of the height.

+(UIImage*)imageWithImage: (UIImage*) sourceImage scaledToWidth: (float) i_width
{
    float oldWidth = sourceImage.size.width;
    float scaleFactor = i_width / oldWidth;

    float newHeight = sourceImage.size.height * scaleFactor;
    float newWidth = oldWidth * scaleFactor;

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

How to resize UIImageView based on UIImage's size/ratio in Swift 3?

It looks like you want to resize an ImageView according to the image ratio and the container view's size, here is the example in Swift (Sorry,the former answer with a bug, I fixed it):

   let containerView = UIView(frame: CGRect(x:0,y:0,width:320,height:500))
   let imageView = UIImageView()

    if let image = UIImage(named: "a_image") {
        let ratio = image.size.width / image.size.height
        if containerView.frame.width > containerView.frame.height {
            let newHeight = containerView.frame.width / ratio
            imageView.frame.size = CGSize(width: containerView.frame.width, height: newHeight)
        }
        else{
            let newWidth = containerView.frame.height * ratio
            imageView.frame.size = CGSize(width: newWidth, height: containerView.frame.height)
        }
    }

How to resize UIImage programmatically to be like setting scaleAspectFill content mode?

I have used this for one of my projects.

extension UIImage
{
    func imageWithSize(size:CGSize) -> UIImage
    {
        var scaledImageRect = CGRect.zero

        let aspectWidth:CGFloat = size.width / self.size.width
        let aspectHeight:CGFloat = size.height / self.size.height

        //max - scaleAspectFill | min - scaleAspectFit
        let aspectRatio:CGFloat = max(aspectWidth, aspectHeight)

        scaledImageRect.size.width = self.size.width * aspectRatio
        scaledImageRect.size.height = self.size.height * aspectRatio
        scaledImageRect.origin.x = (size.width - scaledImageRect.size.width) / 2.0
        scaledImageRect.origin.y = (size.height - scaledImageRect.size.height) / 2.0

        UIGraphicsBeginImageContextWithOptions(size, false, 0)

        self.draw(in: scaledImageRect)

        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return scaledImage!
    }
}

Resize UIImage with aspect ratio?

After you set your screen rect, do something like the following to decide what rect to draw the image in:

float hfactor = value.bounds.size.width / screenRect.size.width;
float vfactor = value.bounds.size.height / screenRect.size.height;

float factor = fmax(hfactor, vfactor);

// Divide the size by the greater of the vertical or horizontal shrinkage factor
float newWidth = value.bounds.size.width / factor;
float newHeight = value.bounds.size.height / factor;

// Then figure out if you need to offset it to center vertically or horizontally
float leftOffset = (screenRect.size.width - newWidth) / 2;
float topOffset = (screenRect.size.height - newHeight) / 2;

CGRect newRect = CGRectMake(leftOffset, topOffset, newWidth, newHeight);

If you don't want to enlarge images smaller than the screenRect, make sure factor is greater than or equal to one (e.g. factor = fmax(factor, 1)).

To get the black background, you would probably just want to set the context color to black and call fillRect before drawing the image.

The simplest way to resize an UIImage?

The simplest way is to set the frame of your UIImageView and set the contentMode to one of the resizing options.

Or you can use this utility method, if you actually need to resize an image:

+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    // In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
    // Pass 1.0 to force exact pixel size.
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}

Example usage:

#import "MYUtil.h"
…
UIImage *myIcon = [MYUtil imageWithImage:myUIImageInstance scaledToSize:CGSizeMake(20, 20)];

UIImage resize aspect fill and crop

Try this:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    imagenUsr = [info objectForKey:UIImagePickerControllerOriginalImage];
    double width = imagenUsr.size.width;
    double height = imagenUsr.size.height;
    double screenWidth = self.view.frame.size.width;
    double apect = width/height;
    double nHeight = screenWidth/ apect;
    self.imgView.frame = CGRectMake(0, 0, screenWidth, nHeight);
    self.imgView.center = self.view.center;
    self.imgView.image = imagenUsr;
}

This will help you keeping the aspect ratio as before.

Another way would be:

self.imgView.contentMode = UIViewContentModeScaleAspectFit;
self.imgView.image = imagenUsr;

Hope this helps.. :)

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