cocoa - swift NSImage 到 CGImage

Question

如何在 Swift 中将 NSImage 转换为 CGImage？在 Objective-C 中我是这样做的:

- (CGImageRef)CGImage {
    NSData *imageData = self.TIFFRepresentation;
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)imageData, NULL);
    CGImageRef maskRef =  CGImageSourceCreateImageAtIndex(source, 0, NULL);
    return maskRef;
}

现在我尝试了:

extension NSImage {
    var CGImage: CGImageRef {
    get {
        let imageData = self.TIFFRepresentation
        let source = CGImageSourceCreateWithData(imageData as CFDataRef, nil)
        let maskRef = CGImageSourceCreateImageAtIndex(source, UInt(0), nil)
        return maskRef;
    }
    }
}

我无法编译，出现错误:无法在 let maskRef ...< 行找到接受提供的参数的“init”的重载/

Answer 1

这是我用来将 NSImage 转换为 CGImage 的内容:

let image = NSImage(named:"image")
if let image = image {
    var imageRect = CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height)
    let imageRef = image.cgImage(forProposedRect: &imageRect, context: nil, hints: nil)
}