Swift – Playground – Core Graphics / Core Text / Custom View


I’m attempting to make a custom UIView component in swift playground. I’ve been able to figure out how to do everything except for render text correctly. I’m not sure if i’m supposed to do this via Core Graphics or Core Text or exactly how to get it working correctly.

As you can see in the image below I want to render text both upside down and right side up on either side of my custom View Component

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    I’ve tried various ways to get the text to work but I keep running aground. If somebody would be able to show me how to modify my playground to add a few text rendering that would be awesome.

    Playground Code

    // Playground - noun: a place where people can play
    import Foundation
    import UIKit
    class RunwayView : UIView {
        var northText : String?
        var southText : String?
        ///Draws the "runway"
        override func drawRect(rect: CGRect) {
            // Setup graphics context
            var ctx = UIGraphicsGetCurrentContext()
            // clear context
            CGContextClearRect(ctx, rect)
            let parentVieBounds = self.bounds
            let width = CGRectGetWidth(parentVieBounds)
            let height = CGRectGetHeight(parentVieBounds)
            // Setup the heights
            let endZoneHeight : CGFloat = 40
            /* Remember y is negative and 0,0 is upper left*/
            //Create EndZones
            CGContextSetRGBFillColor(ctx, 0.8, 0.8, 0.8, 1)
            CGContextFillRect(ctx, CGRectMake(0, 0, width, endZoneHeight))
            CGContextFillRect(ctx, CGRectMake(0, height-endZoneHeight, width, endZoneHeight))
            var northString = NSMutableAttributedString(string: "36")
            var attrs = [NSFontAttributeName : UIFont.systemFontOfSize(16.0)]
            var gString = NSMutableAttributedString(string:"g", attributes:attrs);
            var line = CTLineCreateWithAttributedString(gString)
            CGContextSetTextPosition(ctx, 10, 50);
            CTLineDraw(line, ctx);
            // Clean up
    var outerFrame : UIView = UIView(frame: CGRectMake(20,20,400,400))
    var runway1 : RunwayView = RunwayView(frame: CGRectMake(0,0,30,260))
    var runway2 : RunwayView = RunwayView(frame: CGRectMake(80,0,30,340))
    runway1.transform = CGAffineTransformConcat(CGAffineTransformMakeTranslation(20, 200),
    runway2.transform = CGAffineTransformConcat(CGAffineTransformMakeTranslation(120, 140),
    outerFrame.backgroundColor = UIColor.yellowColor()
    outerFrame.clipsToBounds = true
    // View these elements

    Solutions Collect From Internet About “Swift – Playground – Core Graphics / Core Text / Custom View”

    I wrote a utility function for my app to draw text using CoreText.
    It returns the text size for further processing:

    func drawText(context: CGContextRef, text: NSString, attributes: [String: AnyObject], x: CGFloat, y: CGFloat) -> CGSize {
        let font = attributes[NSFontAttributeName] as UIFont
        let attributedString = NSAttributedString(string: text, attributes: attributes)
        let textSize = text.sizeWithAttributes(attributes)
        // y: Add font.descender (its a negative value) to align the text at the baseline
        let textPath    = CGPathCreateWithRect(CGRect(x: x, y: y + font.descender, width: ceil(textSize.width), height: ceil(textSize.height)), nil)
        let frameSetter = CTFramesetterCreateWithAttributedString(attributedString)
        let frame       = CTFramesetterCreateFrame(frameSetter, CFRange(location: 0, length: attributedString.length), textPath, nil)
        CTFrameDraw(frame, context)
        return textSize

    Call it like so:

    var textAttributes: [String: AnyObject] = [
        NSForegroundColorAttributeName : UIColor(white: 1.0, alpha: 1.0).CGColor,
        NSFontAttributeName : UIFont.systemFontOfSize(17)
    drawText(ctx, text: "Hello, World!", attributes: textAttributes, x: 50, y: 50)

    Hope that helps you.