Changing the shape of a UIView border

Question

I am wondering how I would go about implementing a wave-like border of a UIView. Is this possible through UIView's alone? Or would creating this appearance through a UIImageView be the way to go?

An example might be something similar to:

Thanks for your help!

Answer 1

Here is a code based solution that doesn't require any images. This creates a custom view using UIBezierPath to create the sine waves.

import UIKit

class WavyView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        return nil // TODO
    }

    override func draw(_ rect: CGRect) {
        // Fill the whole background with the darkest blue color
        UIColor(red: 0.329, green: 0.718, blue: 0.875, alpha: 1).set()
        let bg = UIBezierPath(rect: rect)
        bg.fill()

        // Add the first sine wave filled with a very transparent white
        let top1: CGFloat = 17.0
        let wave1 = wavyPath(rect: CGRect(x: 0, y: top1, width: frame.width, height: frame.height - top1), periods: 1.5, amplitude: 21, start: 0.55)
        UIColor(white: 1.0, alpha: 0.1).set()
        wave1.fill()

        // Add the second sine wave over the first
        let top2: CGFloat = 34.0
        let wave2 = wavyPath(rect: CGRect(x: 0, y: top2, width: frame.width, height: frame.height - top2), periods: 1.5, amplitude: 21, start: 0.9)
        UIColor(white: 1.0, alpha: 0.15).set()
        wave2.fill()

        // Add the text
        let paraAttrs = NSMutableParagraphStyle()
        paraAttrs.alignment = .center
        let textRect = CGRect(x: 0, y: frame.maxY - 64, width: frame.width, height: 24)
        let textAttrs = [NSFontAttributeName: UIFont.boldSystemFont(ofSize: 20), NSForegroundColorAttributeName: UIColor(white: 1.0, alpha: 0.9), NSParagraphStyleAttributeName: paraAttrs]
        ("New user? Register here." as NSString).draw(in: textRect, withAttributes: textAttrs)
    }

    // This creates the desired sine wave bezier path
    // rect is the area to fill with the sine wave
    // periods is how may sine waves fit across the width of the frame
    // amplitude is the height in points of the sine wave
    // start is an offset in wavelengths for the left side of the sine wave
    func wavyPath(rect: CGRect, periods: Double, amplitude: Double, start: Double) -> UIBezierPath {
        let path = UIBezierPath()

        // start in the bottom left corner
        path.move(to: CGPoint(x: rect.minX, y: rect.maxY))

        let radsPerPoint = Double(rect.width) / periods / 2.0 / Double.pi
        let radOffset = start * 2 * Double.pi
        let xOffset = Double(rect.minX)
        let yOffset = Double(rect.minY) + amplitude
        // This loops through the width of the frame and calculates and draws each point along the size wave
        // Adjust the "by" value as needed. A smaller value gives smoother curve but takes longer to draw. A larger value is quicker but gives a rougher curve.
        for x in stride(from: 0, to: Double(rect.width), by: 6) {
            let rad = Double(x) / radsPerPoint + radOffset
            let y = sin(rad) * amplitude

            path.addLine(to: CGPoint(x: x + xOffset, y: y + yOffset))
        }

        // Add the last point on the sine wave at the right edge
        let rad = Double(rect.width) / radsPerPoint + radOffset
        let y = sin(rad) * amplitude

        path.addLine(to: CGPoint(x: Double(rect.maxX), y: y + yOffset))

        // Add line from the end of the sine wave to the bottom right corner
        path.addLine(to: CGPoint(x: rect.maxX, y: rect.maxY))
        // Close the path
        path.close()

        return path
    }
}

// This creates the view with the same size as the image posted in the question
let wavy = WavyView(frame: CGRect(x: 0, y: 0, width: 502, height: 172))

The result of running this code in a Swift playground gives the following:

Obviously you can adjust any of the values in the code above to tweak the result.

Answer 2

The easiest approach would be to use a UIImageView . However, it is also possible by creating a custom border for the UIView but that will require a lot of code to draw the shapes.