swift - CIFilter 和 Swift 2 错误 : '_' is not convertible to 'String' + Type of expression is ambiguous without more context

Question

我在 Swift 1.2 中使用了这段代码(改编自 SO 上的 Objective-C 代码片段)来对图像应用模糊效果。

它工作正常，但我无法将其转换为 Swift 2，我不确定我是否理解错误消息，而且我找不到有关更改内容的文档。

错误消息:

'_' is not convertible to 'String'

还有:

Type of expression is ambiguous without more context

适用于 1.2 的扩展:

extension NSImage {
    func gaussianBlurOfRadius(radius: CGFloat) -> NSImage {
        let image = self
        image.lockFocus()
        let beginImage = CIImage(data: image.TIFFRepresentation!)
        // error message highlights the next line
        let params = [kCIInputImageKey: beginImage, kCIInputRadiusKey: radius]
        let filter = CIFilter(name: "CIGaussianBlur", withInputParameters: params)
        var output = filter.valueForKey("outputImage") as! CIImage
        let rect = NSMakeRect(0, 0, self.size.width, self.size.height)
        output.drawInRect(rect, fromRect: rect, operation: NSCompositingOperation.CompositeSourceOver, fraction: 1)
        image.unlockFocus()
        return image
    }
}

更新:

按照 Duncan 的想法，我在声明中添加了显式类型:

let params: [String: AnyObject] = [kCIInputImageKey: beginImage, kCIInputRadiusKey: radius]

但这并不能解决问题，尽管它删除了有关类型歧义的错误消息。

Answer 1

extension NSImage {
    func gaussianBlurOfRadius(radius: CGFloat) -> NSImage {
        let image = self
        image.lockFocus()
        let beginImage = CIImage(data: image.TIFFRepresentation!)!
        let params = [kCIInputImageKey : beginImage, kCIInputRadiusKey: radius]
        let filter = CIFilter(name: "CIGaussianBlur", withInputParameters: params)!
        let output = filter.valueForKey("outputImage") as! CIImage
        let rect = NSMakeRect(0, 0, size.width, size.height)
        output.drawInRect(rect, fromRect: rect, operation: NSCompositingOperation.CompositeSourceOver, fraction: 1)
        image.unlockFocus()
        return image
    }
}

或

extension NSImage {
    func gaussianBlurOfRadius(radius: CGFloat) -> NSImage {
        let image = self
        image.lockFocus()
        let beginImage = CIImage(data: image.TIFFRepresentation!)
        let filter = CIFilter(name: "CIGaussianBlur")!
        filter.setValue(beginImage, forKey: kCIInputImageKey)
        filter.setValue(radius, forKey: kCIInputRadiusKey)
        let output = filter.valueForKey("outputImage") as! CIImage
        let rect = NSMakeRect(0, 0, size.width, size.height)
        output.drawInRect(rect, fromRect: rect, operation: NSCompositingOperation.CompositeSourceOver, fraction: 1)
        image.unlockFocus()
        return image
    }
}