ProgressiveBlurView from My top 3 design “Kisses” I like to add to every app

ProgressiveBlurView.swift

override func layoutSubviews() {
    super.layoutSubviews()

    let filter = (NSClassFromString("CAFilter") as! NSObject.Type)
        .perform(NSSelectorFromString("filterWithType:"), with: "variableBlur")!
        .takeUnretainedValue() as! NSObject

    filter.setValue(20, forKey: "inputRadius")
    filter.setValue(makeMaskImage(), forKey: "inputMaskImage")
    filter.setValue(true, forKey: "inputNormalizeEdges")

    subviews.first?.layer.filters = [filter]

    let featherMask = CAGradientLayer()
    featherMask.frame = bounds
    featherMask.colors = [
        UIColor.black.cgColor,
        UIColor.black.cgColor,
        UIColor.clear.cgColor,
    ]
    featherMask.locations = [0, 0.55, 1]

    layer.mask = featherMask
}