swift - Cannot convert value of type '[String : AnyObject]?' to expected argument type '[NSAttributedStringKey : Any]?'

Question

How to convert values of type '[String : AnyObject]?'to expected argument type '[NSAttributedStringKey : Any]?'?

open class func drawText(context: CGContext, text: String, point: CGPoint, 
align: NSTextAlignment, attributes: [String : AnyObject]?)
{
    var point = point

    if align == .center
    {
        point.x -= text.size(withAttributes: attributes).width / 2.0
    }
    else if align == .right
    {
        point.x -= text.size(withAttributes: attributes).width
    }

    NSUIGraphicsPushContext(context)

    (text as NSString).draw(at: point, withAttributes: attributes)

    NSUIGraphicsPopContext()
}

Answer 1

This is a new feature of Swift 4. All the Cocoa methods that take string identifiers and/or dictionary keys now have their own types for the keys. The reason for this is to add a bit of type safety—in the old regime, it was possible to accidentally pass a String constant by mistake that was meant to be used with some other API, but now in Swift 4, this will result in a compilation error.

Change your method signature to:

open class func drawText(context: CGContext, text: String, point: CGPoint,
    align: NSTextAlignment, attributes: [NSAttributedString.Key : Any]?)

EDIT: Updated for Swift 4.2! NSAttributedStringKey has been renamed to NSAttributedString.Key.