图片模糊化处理

BlurImage.swift

import Accelerate
import UIKit

extension UIImage {
    
    private static let cache = NSCache<NSString, UIImage>()
    
    func bluredImage(factor: CGFloat) -> UIImage? {
        var blur = factor
        if blur < 0 || blur > 1 {
            blur = 0.5
        }
        
        var boxSize: UInt32 = UInt32(blur * 40)
        boxSize -= boxSize % 2 + 1
        
        guard let img = cgImage,
            let inProvider = img.dataProvider,
            let inBitmapData =  inProvider.data,
            let sourceData = UnsafeMutablePointer(mutating: CFDataGetBytePtr(inBitmapData)) else {
            return nil
        }
        
        var inBuffer = vImage_Buffer(data: sourceData,
                                     height: vImagePixelCount(img.width),
                                     width: vImagePixelCount(img.height),
                                     rowBytes: img.bytesPerRow)
       
        guard let pixelBuffer = malloc(img.height * img.bytesPerRow) else {
            return nil
        }
        
        var outBuffer = vImage_Buffer(data: pixelBuffer,
                                      height: vImagePixelCount(img.width),
                                      width: vImagePixelCount(img.height),
                                      rowBytes: img.bytesPerRow)
        
        guard vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, nil, 0, 0, boxSize, boxSize,
                                         nil, vImage_Flags(kvImageEdgeExtend)) == 0 else {
            return nil
        }
        
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        guard let ctx = CGContext(data: outBuffer.data,
                            width: Int(outBuffer.width),
                            height: Int(outBuffer.height),
                            bitsPerComponent: 8,
                            bytesPerRow: outBuffer.rowBytes,
                            space: colorSpace,
                            bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue),
            let imgRef = ctx.makeImage() else {
                return nil
        }

        defer {
            pixelBuffer.deallocate()
            sourceData.deallocate()
        }
        return UIImage(cgImage: imgRef)
    }
    
    func bluredImage(factor: CGFloat, forUrl: String?) -> UIImage? {
        guard let url = forUrl, !url.isEmpty else {
            return bluredImage(factor: factor)
        }
        let key = NSString(string: "\(url)#factor=\(factor)")
        var image = UIImage.cache.object(forKey: key)
        if image == nil, let blurImg = bluredImage(factor: factor) {
            image = blurImg
            UIImage.cache.setObject(blurImg, forKey: key)
        }
        return image
    }
}