SwiftyDraw is a simple, light-weight drawing framework written in Swift. SwiftyDraw is built using Core Gaphics and is very easy to implement.

• iOS 9.1+
• Swift 5.0

SwiftyDraw is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'SwiftyDraw'

SwiftyDraw is also available through Carthage. To install, you can simply add the following line to your Cartfile for the latest version of SwiftyDraw.

github "awalz/SwiftyDraw" "master"

Simply copy the contents of the Source folder into your project.

Using SwiftyDraw is very simple:

Simply create a SwiftyDrawView and add it to your View Controller:

let drawView = SwiftyDrawView(frame: self.view.frame)
self.view.addSubview(drawView)

By default, the view will automatically respond to touch gestures and begin drawing. The default color is black.

To disable drawing, simply set the isEnabled property to false:

drawView.isEnabled = false

For drawing, we use Brush to keep track of styles like width, color, etc.. We have multiple different default brushes, you can use as follows:

drawView.brush = Brush.default

The default brushed are:

public static var `default`: Brush { get } // black, width 3
public static var thin     : Brush { get } // black, width 2
public static var medium   : Brush { get } // black, width 7
public static var thick    : Brush { get } // black, width 10
public static var marker   : Brush { get } // flat red-ish, width 12
public static var eraser   : Brush { get } // white, width 8; currently this fakes an eraser by using the canvas' background color to draw

SwiftyDrawView supports drawing-angle-adjusted brushes. Effectively, that means, if the user (using an Pencil) draws with the tip of the pencil, the brush will reduce its width a little. If the user draws at a very low angle, with the side of the pencil, the brush will be a little thicker. You can modify this behavior by setting adjustedWidthFactor of a brush. If you increase the number (to, say, 5) the changes will increase. If you reduce the number to 0, the width will not be adjusted at all. The default value is 1 which causes a slight increase in width.

This is an opt-in feature. That means, in shouldBeginDrawingIn, you need to manually put drawingView.brush.adjustWidth(for: touch), to make it work. That is, because you might not want to use it if you have implemented a zoom feature and want to disable it while the user is zooming to get better results.

For more customization, you can modify the different properties of a brush to fit your needs.

The color of a line stroke can be changed by adjusting the color property of a brush. SwiftyDraw accepts any UIColor:

drawView.brush.color = .red

or

drawView.brush.color = UIColor(colorLiteralRed: 0.75, green: 0.50, blue: 0.88, alpha: 1.0)

The width of a line stroke can be changed by adjusting the width property of a brush. SwiftyDraw accepts any positive CGFloat:

drawView.brush.width = CGFloat(5.0)

The opacity of a line stroke can be changed by adjusting the lineOpacity property. SwiftyDraw accepts a CGFloat between 0. and 1.0:

drawView.brush.opacity = CGFloat(0.5)

If you wish to clear the entire canvas, simply call the clear function:

drawView.clear()

drawView.undo()

...and redo:

drawView.redo()

Apple Pencil can be used for drawing in a SwiftyDrawView, just like a finger.
Special features, however, regarding Apple Pencil 2 are only supported on iOS 12.1 and above versions.

Apple Pencil interaction is enabled by default, but you can set drawView.isPencilInteractive to change that setting.

When double tapping the pencil, SwiftyDraw will check the user preferences set in the system. If the preference is set to switch to eraser, SwiftyDraw will switch between normal and erasing mode; if set to last used tool, SwiftyDraw will switch between current and previous brush.

SwiftyDraw has delegate functions to notify you when a user is interacting with a SwiftDrawView. To access these delegate methods, simply make your View Controller conform to the SwiftyDrawViewDelegate protocol:

class ViewController: UIViewController, SwiftyDrawViewDelegate

/// SwiftyDrawViewDelegate called when a touch gesture should begin on the SwiftyDrawView using given touch type
func swiftyDraw(shouldBeginDrawingIn drawingView: SwiftyDrawView, using touch: UITouch) -> Bool
    
/// SwiftyDrawViewDelegate called when a touch gesture begins on the SwiftyDrawView.
func swiftyDraw(didBeginDrawingIn drawingView: SwiftyDrawView, using touch: UITouch)

/// SwiftyDrawViewDelegate called when touch gestures continue on the SwiftyDrawView.
func swiftyDraw(isDrawingIn drawingView: SwiftyDrawView, using touch: UITouch)
    
/// SwiftyDrawViewDelegate called when touches gestures finish on the SwiftyDrawView.
func swiftyDraw(didFinishDrawingIn drawingView: SwiftyDrawView, using touch: UITouch)
    
/// SwiftyDrawViewDelegate called when there is an issue registering touch gestures on the  SwiftyDrawView.
func swiftyDraw(didCancelDrawingIn drawingView: SwiftyDrawView, using touch: UITouch)

This is a project built by Awalz and maintained & improved by LinusGeffarth.

If you would like to propose any enhancements, bug fixes, etc., feel free to create a pull request or an issue respectively.

If you have any questions, or just want to say hi, you can reach out to me via Twitter, or email.

SwiftyDraw is available under the MIT license. See the LICENSE file for more info.