Mark Bragg - 4 months ago 43

Swift Question

I've been trying to figure out how to use UIBezierPath for this project, but I don't know how to implement this kind of drawing. I can draw a circle and arcs and straight lines, but I am feeling pretty lost on this one. Appreciate the help

Answer

To draw a sine wave on a `UIBezierPath`

called `path`

, draw a number of line segments using `path.addLine(to:)`

. The trick is to convert the angle (`0`

to `360`

) to the `x`

coordinate of a point, and `sin(x)`

to the `y`

coordinate of a point.

Here is an example:

```
class SineView: UIView{
let graphWidth: CGFloat = 0.8 // Graph is 80% of the width of the view
let amplitude: CGFloat = 0.3 // Amplitude of sine wave is 30% of view height
override func draw(_ rect: CGRect) {
let width = rect.width
let height = rect.height
let origin = CGPoint(x: width * (1 - graphWidth) / 2, y: height * 0.50)
let path = UIBezierPath()
path.move(to: origin)
for angle in stride(from: 5.0, through: 360.0, by: 5.0) {
let x = origin.x + CGFloat(angle/360.0) * width * graphWidth
let y = origin.y - CGFloat(sin(angle/180.0 * Double.pi)) * height * amplitude
path.addLine(to: CGPoint(x: x, y: y))
}
UIColor.black.setStroke()
path.stroke()
}
}
let sineView = SineView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
sineView.backgroundColor = .white
```

Here it is running in a Playground:

@Rob updated this code making it `@IBDesignable`

with `@IBInspectable`

properties in addition to adding a `periods`

property. Check out his answer here.