xcode iPhone，如何将一张图像叠加到另一张图像上以创建要保存的新图像？（水印）

iPhone, how does one overlay one image onto another to create a new image to save? (watermark)

提问by SolidSnake4444

Basically I want to take an image that the user chooses from their photo library and then apply a watermark, a triangle in the lower right that has the app name on it. I have the second image already made with a transparent layer in photoshop.

基本上我想拍摄用户从他们的照片库中选择的图像，然后应用水印，右下角有一个三角形，上面有应用程序名称。我已经在photoshop中用透明层制作了第二张图像。

I tried a function, which I can't remember the exact name, but it involved CGIImages and masks. This combines the two images, but as a mask, which made the image darker where the transparent layer was and the images were not merged per se, just masked.

我尝试了一个函数，我不记得确切的名称，但它涉及 CGIImages 和掩码。这将两个图像组合在一起，但作为一个遮罩，它使透明层所在的图像更暗，并且图像本身没有合并，只是被遮罩了。

How would I get the watermark image to merge with another image, to make a UIImage, without displaying the images on the screen?

如何让水印图像与另一个图像合并，制作一个 UIImage，而不在屏幕上显示图像？

Thank you.

谢谢你。

回答by omz

It's pretty easy:

这很容易：

UIImage *backgroundImage = [UIImage imageNamed:@"image.png"];
UIImage *watermarkImage = [UIImage imageNamed:@"watermark.png"];

UIGraphicsBeginImageContext(backgroundImage.size);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[watermarkImage drawInRect:CGRectMake(backgroundImage.size.width - watermarkImage.size.width, backgroundImage.size.height - watermarkImage.size.height, watermarkImage.size.width, watermarkImage.size.height)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

If you want the background and watermark to be of the same size then use this code

如果您希望背景和水印的大小相同，请使用此代码

...
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[watermarkImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
...

回答by CodeMonkey

The solution provided by omzalso works in Swift, like so:

omz提供的解决方案也适用于Swift，如下所示：

let backgroundImage = UIImage(named: "image.png")!
let watermarkImage = UIImage(named: "watermark.png")!

UIGraphicsBeginImageContextWithOptions(backgroundImage.size, false, 0.0)
backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: backgroundImage.size.width, height: backgroundImage.size.height))
watermarkImage.draw(in: CGRect(x: backgroundImage.size.width - watermarkImage.size.width, y: backgroundImage.size.height - watermarkImage.size.height, width: watermarkImage.size.width, height: watermarkImage.size.height))
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

回答by Sachin Rasane

SWIFT 4

快速 4

                    let backgroundImage = imageData!
                    let watermarkImage = #imageLiteral(resourceName: "jodi_url_icon")

                    UIGraphicsBeginImageContextWithOptions(backgroundImage.size, false, 0.0)
                    backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: backgroundImage.size.width, height: backgroundImage.size.height))
                    watermarkImage.draw(in: CGRect(x: 10, y: 10, width: watermarkImage.size.width, height: backgroundImage.size.height - 40))

                    let result = UIGraphicsGetImageFromCurrentImageContext()
                    UIGraphicsEndImageContext()
                    self.imgaeView.image = result

Use result to UIImageView, tested.

使用结果到 UIImageView，经过测试。

回答by Parvez Belim

You can use this method, which is very dynamic and you can specify the starting position of the second image and total size of the image.

你可以使用这个方法，它非常动态，你可以指定第二张图像的起始位置和图像的总大小。

-(UIImage *) addImageToImage:(UIImage *)img withImage2:(UIImage *)img2 andRect:(CGRect)cropRect withImageWidth:(int) width{

    CGSize size = CGSizeMake(width,40);
    UIGraphicsBeginImageContext(size);

    CGPoint pointImg1 = CGPointMake(0,0);
    [img drawAtPoint:pointImg1];

    CGPoint pointImg2 = cropRect.origin;
    [img2 drawAtPoint: pointImg2];

    UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return result;

}

回答by Ali Alaoi

SWIFT 5 Function:

SWIFT 5 功能：

func addWaterMark(image: UIImage) -> UIImage {
        let backgroundImage = image//UIImage(named: "image.png")
        let watermarkImage = UIImage(named: "waterMark.png")

        UIGraphicsBeginImageContextWithOptions(backgroundImage.size, false, 0.0)
        backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: backgroundImage.size.width, height: backgroundImage.size.height))
        watermarkImage!.draw(in: CGRect(x: backgroundImage.size.width - watermarkImage!.size.width, y: backgroundImage.size.height - watermarkImage!.size.height, width: watermarkImage!.size.width, height: watermarkImage!.size.height))
        let result = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return result!
    }