Let's draw some strings! There's plenty of text-drawing capabilities in iOS and OS X, with full frameworks like Text Kit (or the lower-level Core Text) dedicated to the task. Today, we'll start looking at these capabilities by using Core Graphics and UIKit to draw a multiline string.
Sometimes we need to draw text ourselves, “manually”. This can be helpful when optimizing for scrolling performance, or when complete customization is necessary.
First we'll need a view to draw into, we'll make a new UIView, and override
Next, we'll start implementing our
drawRect function with a few variables. We'll choose a font, then setup a paragraph style to make our text multiline, with some tall lines.
We'll also setup some drawing options to tell the system we want multiline text:
let textFont = UIFont(name: "Avenir Next", size: 17.0)! let paragraphStyle = NSMutableParagraphStyle() paragraphStyle.lineHeightMultiple = 1.2 paragraphStyle.lineBreakMode = .ByWordWrapping let drawingOptions: NSStringDrawingOptions = [ .UsesLineFragmentOrigin, .UsesFontLeading]
We'll save these off into a
textAttributes dictionary. Next, we'll need to figure out what rectangle we'll be drawing our text into.
We'll use the
boundingRectWithSize function to find out how tall it will be when constrained to the width of our view:
let textRect = (text as NSString) .boundingRectWithSize( CGSizeMake(bounds.size.width, CGFloat.max), options: drawingOptions, attributes: textAttributes, context: nil)
Then we'll just pass that calculated textRect into a call to drawWithRect:
(text as NSString).drawWithRect(textRect, options: drawingOptions, attributes: textAttributes, context: nil)