I am using the code below to learn more about drawing but I am getting an ambiguous error on the line not sure how to resolve this. Please advise how to code this. Thanks
let context = NSGraphicsContext.current()?.cgContext
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
** let context = NSGraphicsContext.current()?.cgContext**
let length = CGPoint(x: 100, y: 100)
let p1 = CGPoint(x: 200, y: 200)
let shape = "square"
context!.beginPath()
context!.move(to: p1)
if shape == "line" {
let pointEnd = CGPoint(x: p1.x + length.x, y: p1.y + length.y)
context!.addLine(to: pointEnd)
} else if shape == "square" {
let p2 = CGPoint(x: p1.x + length.x, y: p1.y)
let p3 = CGPoint(x: p1.x + length.x, y: p1.y + length.y)
let p4 = CGPoint(x: p1.x, y: p1.y + length.y)
context!.addLine(to: p2)
context!.addLine(to: p3)
context!.addLine(to: p4)
context!.addLine(to: p1)
}
context!.setStrokeColor(red: 1, green: 1, blue: 1, alpha: 1.0)
context!.setFillColor(red: 0, green: 1, blue: 0, alpha: 1)
context!.setLineWidth(2.0)
context!.strokePath()
let textColor = NSColor(calibratedRed: 1, green: 1, blue: 1, alpha: 1.0)
let textColorB = NSColor(calibratedRed: 1, green: 1, blue: 1, alpha: 0.0)
let rect = CGRect(x: 200, y: 200, width: 30, height: 130)
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
let attr = [NSAttributedString.Key.paragraphStyle: paragraphStyle, NSAttributedString.Key.foregroundColor: textColor, NSAttributedString.Key.backgroundColor: textColorB, NSAttributedString.Key.font:NSFont.init(name: "HelveticaNeue-Thin", size: 14)]
let q: NSString = "hello, world"
let center = CGPoint(x: 0, y: 0)
q.draw(at: center, withAttributes: attr as [NSAttributedString.Key : Any])
}
}
In Swift, NSGraphicsContext.current is a class property, not a function, so you can't have () after it:
let context = NSGraphicsContext.current?.cgContext
Also, it's (strictly speaking) correct to store the optional result as context and to reference it later as context!, but it's poor Swift coding practice, even if you're sure that it will never be nil. Instead, you could do something like this:
guard let context = NSGraphicsContext.current?.cgContext else {
// handle the error somehow
}
Or, you can avoid having to deal with an error by making the drawing conditional, something like:
if let context = NSGraphicsContext.current?.cgContext {
let length = CGPoint(x: 100, y: 100)
let p1 = CGPoint(x: 200, y: 200)
let shape = "square"
context.beginPath()
context.move(to: p1)
if shape == "line" {
let pointEnd = CGPoint(x: p1.x + length.x, y: p1.y + length.y)
context.addLine(to: pointEnd)
} else if shape == "square" {
let p2 = CGPoint(x: p1.x + length.x, y: p1.y)
let p3 = CGPoint(x: p1.x + length.x, y: p1.y + length.y)
let p4 = CGPoint(x: p1.x, y: p1.y + length.y)
context.addLine(to: p2)
context.addLine(to: p3)
context.addLine(to: p4)
context.addLine(to: p1)
}
context.setStrokeColor(red: 1, green: 1, blue: 1, alpha: 1.0)
context.setFillColor(red: 0, green: 1, blue: 0, alpha: 1)
context.setLineWidth(2.0)
context.strokePath()
}
…
