新生成的图像质量很低ios swift

Question

我一直在使用在线教程制作简单的照片应用程序。我创建了上传或捕获图像的应用程序，可以在图像上添加文本并保存。但问题是保存图像质量很差。它也将应用程序按钮和条形图带到输出图像上。

这就是我生成最终图像的方式

func save() {

        //Create the meme
        var meme = Meme( textField: topTextField.text!,textField2: bottomTextField.text!, image:
            imageView.image, memedImage: memedImage)
    }

func generateMemedImage() -> UIImage
    {
        // Render view to an image
        save()

        UIGraphicsBeginImageContext(self.view.frame.size)
        self.view.drawViewHierarchyInRect(self.view.frame,
            afterScreenUpdates: true)
        memedImage =
        UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return memedImage
    }

    @IBAction func saveImage(sender: AnyObject) {
        generateMemedImage()

        UIImageWriteToSavedPhotosAlbum(memedImage, nil, nil, nil)
    }

无论如何都要用质量输出来做到这一点？

Answer 1

您没有使用方面调整大小，您还需要关注视网膜调整大小

Swift 4

func resizeImageWithAspect(image: UIImage,scaledToMaxWidth width:CGFloat,maxHeight height :CGFloat)->UIImage? {
    let oldWidth = image.size.width;
    let oldHeight = image.size.height;

    let scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;

    let newHeight = oldHeight * scaleFactor;
    let newWidth = oldWidth * scaleFactor;
    let newSize = CGSize(width: newWidth, height: newHeight)

    UIGraphicsBeginImageContextWithOptions(newSize,false,UIScreen.main.scale);

    image.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height));
    let newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage
}

Swift＆lt; 4

private func _resizeWithAspect_doResize(image: UIImage,size: CGSize)->UIImage{
    if UIScreen.mainScreen().respondsToSelector("scale"){
        UIGraphicsBeginImageContextWithOptions(size,false,UIScreen.mainScreen().scale);
    }
    else
    {
         UIGraphicsBeginImageContext(size);
    }

    image.drawInRect(CGRectMake(0, 0, size.width, size.height));
    var newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

func resizeImageWithAspect(image: UIImage,scaledToMaxWidth width:CGFloat,maxHeight height :CGFloat)->UIImage
{
    let oldWidth = image.size.width;
    let oldHeight = image.size.height;

    let scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;

    let newHeight = oldHeight * scaleFactor;
    let newWidth = oldWidth * scaleFactor;
    let newSize = CGSizeMake(newWidth, newHeight);

    return self._resizeWithAspect_doResize(image, size: newSize);
}

使用：

 var image : UIImage = yourImageClassInstance.resizeImageWithAspect(image:UIImage(named: "yourImg"),scaledToMaxWidth: 35.0, maxHeight: 45.0);