Drawing rotated text with NSString drawInRect

Question

I found this answer on how to draw rotated text with NSString drawInRect:, but I\'m not sure how it works since it only sort of works for me: https://discussions.apple.com/t

Answer 1

KoNew's Solution in Swift:

extension NSString {

    func drawWithBasePoint(basePoint:CGPoint, angle:CGFloat, font:UIFont) {

        var attrs: NSDictionary = [
            NSFontAttributeName: font
        ]

        var textSize:CGSize = self.sizeWithAttributes(attrs as [NSObject : AnyObject])

        // sizeWithAttributes is only effective with single line NSString text 
        // use boundingRectWithSize for multi line text

        var context: CGContextRef =   UIGraphicsGetCurrentContext()

        var t:CGAffineTransform   =   CGAffineTransformMakeTranslation(basePoint.x, basePoint.y)
        var r:CGAffineTransform   =   CGAffineTransformMakeRotation(angle)


        CGContextConcatCTM(context, t)
        CGContextConcatCTM(context, r)


        self.drawAtPoint(CGPointMake(-1 * textSize.width / 2, -1 * textSize.height / 2), withAttributes: attrs as [NSObject : AnyObject])


        CGContextConcatCTM(context, CGAffineTransformInvert(r))
        CGContextConcatCTM(context, CGAffineTransformInvert(t))


    }


}

To use:

let fieldFont = UIFont(name: "Helvetica Neue", size: 14)

myNSString.drawWithBasePoint(CGPointMake(bounds.width/2, bounds.height/2), angle: CGFloat(-M_PI_2), font: fieldFont!)