iOS 8 之后，苹果推出了 UIVisualEffectView 高斯模糊效果，但是有时，我们仅需要轻微的模糊效果，而且模糊程度是可控的。
这时可以使用 vImage 来进行模糊效果处理。

首先导入框架

import Accelerate

    // MARK:- 图片模糊效果处理
    /// 图片模糊效果处理
    /// - parameter image: 需要处理的图片
    /// - parameter level: 模糊程度（0~1）
    func blurry(_ image: UIImage, level: CGFloat) -> UIImage {
        
        // 处理模糊程度, 防止超出
        var levelValue: CGFloat = level
        if level < 0 {
            levelValue = 0.1
        } else if level > 1.0 {
            levelValue = 1.0
        }
        
        // boxSize 必须大于 0
        var boxSize = Int(levelValue * 100)
        boxSize -= (boxSize % 2) + 1
        
        let _cgImage = image.cgImage
        
        // 图像缓存: 输入缓存、输出缓存
        var inBuffer = vImage_Buffer()
        var outBuffer = vImage_Buffer()
        var error = vImage_Error()
        
        
        let inProvider = _cgImage?.dataProvider
        let inBitmapData = inProvider?.data
        
        inBuffer.width = vImagePixelCount((_cgImage?.width)!)
        inBuffer.height = vImagePixelCount((_cgImage?.height)!)
        inBuffer.rowBytes = (_cgImage?.bytesPerRow)!
        inBuffer.data = UnsafeMutableRawPointer(mutating: CFDataGetBytePtr(inBitmapData!))
        
        // 像素缓存
        let pixelBuffer = malloc((_cgImage?.bytesPerRow)! * (_cgImage?.height)!)
        outBuffer.data = pixelBuffer
        outBuffer.width = vImagePixelCount((_cgImage?.width)!)
        outBuffer.height = vImagePixelCount((_cgImage?.height)!)
        outBuffer.rowBytes = (_cgImage?.bytesPerRow)!
        
        // 中间缓存区, 抗锯齿
        let pixelBuffer2 = malloc((_cgImage?.bytesPerRow)! * (_cgImage?.height)!)
        var outBuffer2 = vImage_Buffer()
        outBuffer2.data = pixelBuffer2
        outBuffer2.width = vImagePixelCount((_cgImage?.width)!)
        outBuffer2.height = vImagePixelCount((_cgImage?.height)!)
        outBuffer2.rowBytes = (_cgImage?.bytesPerRow)!
        
        
        error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer2, nil, 0, 0, UInt32(boxSize), UInt32(boxSize), nil, vImage_Flags(kvImageEdgeExtend))
        error = vImageBoxConvolve_ARGB8888(&outBuffer2, &outBuffer, nil, 0, 0, UInt32(boxSize), UInt32(boxSize), nil, vImage_Flags(kvImageEdgeExtend))
        
        if error != kvImageNoError {
            debugPrint(error)
        }
        
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let ctx = CGContext(data: outBuffer.data, width: Int(outBuffer.width), height: Int(outBuffer.height), bitsPerComponent: 8, bytesPerRow: outBuffer.rowBytes, space: colorSpace, bitmapInfo: (_cgImage?.bitmapInfo.rawValue)!)
        
        let finalCGImage = ctx!.makeImage()
        let finalImage = UIImage(cgImage: finalCGImage!)
        
        free(pixelBuffer!)
        free(pixelBuffer2!)

        return finalImage
    }

> 效果如下：

IMG_0740.PNG

IMG_0742.PNG