How can I resize the UIImage to specific size

问题:

In my app, I am taking picture with camera and displaying it in 320*320 UIView. But as the image resolution is more than that of UIView its kinda look squeezed. Is there any way I can resize that image?

回答1:

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;
}

回答2:

I do this, but first I enable the photo picker to editable so it is default 1:1 aspect, like so:

imgPicker.allowsImageEditing = YES; //I think this is what you're really looking for

then I resize the image using this method:

-(UIImage*)resizeImage:(UIImage*)image{
    CGSize newSize = CGSizeMake(480.0, 480.0);
    UIGraphicsBeginImageContext(newSize);
        [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
        UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}