Change UIImage ratio to fb cover in iphone Programmatically

Question

I am picking an image from image picker and then i want to change ratios for that image as facebook cover. i have an image let suppose its resolution ia 640 widht and 480 height and i want to change it for facebook cover(851 pixels wide and 315 pixels tall) how will i do that programmatically in iphone Check this link for cover picture details Thanks.

Answer 1

 Use this Method to Resize the image according to the given content mode, taking into account the image's orientation...

- (UIImage *)resizedImageWithContentMode:(UIViewContentMode)contentMode bounds:(CGSize)bounds
                interpolationQuality:(CGInterpolationQuality)quality {

CGFloat horizontalRatio = bounds.width / self.size.width;
CGFloat verticalRatio = bounds.height / self.size.height;
CGFloat ratio;

switch (contentMode) {
    case UIViewContentModeScaleAspectFill:
        ratio = MAX(horizontalRatio, verticalRatio);
        break;

    case UIViewContentModeScaleAspectFit:
        ratio = MIN(horizontalRatio, verticalRatio);
        break;

    default:
        [NSException raise:NSInvalidArgumentException format:@"Unsupported content mode:  %d", contentMode];
}

CGSize newSize = CGSizeMake(self.size.width * ratio, self.size.height * ratio);

return [self resizedImage:newSize interpolationQuality:quality];

}

and go this this link for more detail, Resizing Uiimage in right way .