KView is a custom IBDesignable UIView written in Swift 3. KView offers gradient background, border color, border width, corner radius.

KView.swift

// Copyright © 2017 Kalpesh Talkar. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//  For support: https://gist.github.com/KalpeshTalkar/5bd48de786227cdf7683d5c239374842
//

import UIKit

@IBDesignable
class KView: UIView {

    // MARK: - IBInspectable properties

    /// Renders vertical gradient if true else horizontal
    @IBInspectable public var verticalGradient: Bool = true {
        didSet {
            updateUI()
        }
    }

    /// Start color of the gradient
    @IBInspectable public var startColor: UIColor = .clear {
        didSet {
            updateUI()
        }
    }

    /// End color of the gradient
    @IBInspectable public var endColor: UIColor = .clear {
        didSet {
            updateUI()
        }
    }

    /// Border color of the view
    @IBInspectable public var borderColor: UIColor = .clear {
        didSet {
            updateUI()
        }
    }

    /// Border width of the view
    @IBInspectable public var borderWidth: CGFloat = 0 {
        didSet {
            updateUI()
        }
    }

    /// Corner radius of the view
    @IBInspectable public var cornerRadius: CGFloat = 0 {
        didSet {
            updateUI()
        }
    }

    // MARK: - Variables
    private var gradientlayer = CAGradientLayer()

    // MARK: - init methods
    override public init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }

    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupUI()
    }

    // MARK: - Layout
    override public func layoutSubviews() {
        super.layoutSubviews()
        updateFrame()
    }

    // MARK: - UI Setup
    private func setupUI() {
        gradientlayer = CAGradientLayer()
        updateUI()
        layer.addSublayer(gradientlayer)
    }

    // MARK: - Update frame
    private func updateFrame() {
        gradientlayer.frame = bounds
    }

    // MARK: - Update UI
    private func updateUI() {
        gradientlayer.colors = [startColor.cgColor, endColor.cgColor]
        if verticalGradient {
            gradientlayer.startPoint = CGPoint(x: 0, y: 0)
            gradientlayer.endPoint = CGPoint(x: 0, y: 1)
        } else {
            gradientlayer.startPoint = CGPoint(x: 0, y: 0)
            gradientlayer.endPoint = CGPoint(x: 1, y: 0)
        }
        layer.cornerRadius = cornerRadius
        layer.borderWidth = borderWidth
        layer.borderColor = borderColor.cgColor
        if cornerRadius > 0 {
            layer.masksToBounds = true
        }
        updateFrame()
    }

}