如何在Swift中添加半径为2pt的模糊? [英] How can I add blur with 2pt of radius in Swift?

问题描述

我想创建类似的东西

我已经尝试过这个:

var blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Dark)
var blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
view.addSubview(blurEffectView)

但是会产生非常暗的模糊.但是我需要半径为2pt的完全暗的模糊(黑色).

but this creates very dark blur. But I need exactly dark blur(black color) with 2pt of radius.

我可以在Swift中实现吗?

Can I achieve that in Swift?

推荐答案

您无法控制UIVisualEffectView的模糊半径.通过对要模糊的视图进行快照，然后将CoreImage的"CIGaussianBlur"过滤器应用于该快照，然后将模糊的图像显示在要模糊的视图正上方的UIImageView中，可以实现所需的功能.使用CIGaussianBlur，您可以将模糊半径应用于任意长度.

You can't control the radius of the blur of a UIVisualEffectView. You can achieve what you want by snapshotting the view you want to blur and applying a CoreImage's "CIGaussianBlur" filter to that snapshot then displaying the blurred image in a UIImageView placed directly above the view you want to blur. With CIGaussianBlur you can apply a blur radius to an arbitrary length.

您可以在UIView上使用扩展名，以使其更加方便:

You can use an extension on UIView to make this more convenient:

extension UIView
{
    func snapshotView(scale scale: CGFloat = 0.0, isOpaque: Bool = true) -> UIImage
    {
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, opaque, scale)
        self.drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image
    }

    func blur(blurRadius blurRadius: CGFloat) -> UIImage?
    {
        guard let blur = CIFilter(name: "CIGaussianBlur") else { return nil }

        let image = self.snapshotView(scale: 1.0, isOpaque: true)
        blur.setValue(CIImage(image: image), forKey: kCIInputImageKey)
        blur.setValue(blurRadius, forKey: kCIInputRadiusKey)

        let ciContext  = CIContext(options: nil)

        let result = blur.valueForKey(kCIOutputImageKey) as! CIImage!

        let boundingRect = CGRect(x: 0,
                                  y: 0,
                                  width: frame.width,
                                  height: frame.height)

        let cgImage = ciContext.createCGImage(result, fromRect: boundingRect)

        return UIImage(CGImage: cgImage)
    }
}

然后，您可以添加一个半透明的叠加层来确定模糊的程度，例如:

Then you can add a semi transparent overlay to determine how dark the blur is, for example:

let overlay = UIView()
overlay.frame = view.bounds
overlay.backgroundColor = UIColor(white: 0.0, alpha: 0.30)
viewIWantToBlur.addSubview(overlay)
let image = viewIWantToBlur.blur(blurRadius: 2.0)
imageView.image = image

有关此方法的更多信息和更可靠的工作示例，您可以在此处看到.您应该是注意这是性能密集型.

For more information on this method and a more robust working example you can see here. You should be aware that this is performance intensive.

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