Here’s how you can resize the image while preserving its aspect ratio. The code below is from a category for UIImage:
+ (UIImage*)imageWithImage:(UIImage *)image 
              scaledToSize:(CGSize)newSize
{
    float heightToWidthRatio = image.size.height / image.size.width;
    float scaleFactor = 1;
    if(heightToWidthRatio > 0) {
        scaleFactor = newSize.height / image.size.height;
    } else {
        scaleFactor = newSize.width / image.size.width;
    }
    CGSize newSize2 = newSize;
    newSize2.width = image.size.width * scaleFactor;
    newSize2.height = image.size.height * scaleFactor;
    UIGraphicsBeginImageContext(newSize2);
    [image drawInRect:CGRectMake(0,0,newSize2.width,newSize2.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}
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solved How can I resize the UIImage to specific size