Helpful Swift Extensions

Array+Extension.swift

import UIKit

extension Array where Element == NSLayoutConstraint {
    
    /// Activates each constraint in an array of `NSLayoutConstraint`.
    ///
    /// Example usage: `[view.heightAnchor.constraint(equalToConstant: 30), view.widthAnchor.constraint(equalToConstant: 30)].activate()`
    func activate() {
        NSLayoutConstraint.activate(self)
    }
    
    /// Deactivates each constraint in an array of `NSLayoutConstraint`.
    ///
    /// Example usage: `[view.heightAnchor.constraint(equalToConstant: 30), view.widthAnchor.constraint(equalToConstant: 30)].deactivate()`
    func deactivate() {
        NSLayoutConstraint.deactivate(self)
    }
    
}

Dictionary+Extension.swift

import Foundation

extension Dictionary {
    
    @discardableResult
    /// Combines the contents of a given dictionary into the current dictionary. If a `key` already exists, function will update the value.
    /// - Parameter dictionary: New dictionary to merge into the current dictionary.
    /// - Returns: Returns the current dictionary with merged `key: values` pairs.
    mutating func merge(_ dictionary: [Key: Value]) -> [Key: Value] {
        for (key, value) in dictionary {
            updateValue(value, forKey: key)
        }
        return self
    }
    
}

NSMutableAttributedString+Extensions.swift

import UIKit

extension NSMutableAttributedString {
    
    /**
     Appends an attributed string to an `NSMutableAttributedString`
     - Parameter text: Text intended to be formatted.
     - Parameter font: Preferred `UIFont` of the attributed text.
     - Parameter color: Preferred `UIColor` of the attributed text.
     - Returns: Returns the `NSMutableAttributedString` with appended text.
        
     Example usage:
     ```
     let label = UILabel()
     label.attributedText = NSMutableAttributedString()
         .append("This text will be 12 point font and black. ", withFont: .systemFont(ofSize: 12), color: .black)
         .append("This text will be 15 point font and gray.", withFont: .systemFont(ofSize: 15), color: .gray)
     ```
    */
    @discardableResult
    func append(_ text: String, withFont font: UIFont, color: UIColor = .label) -> NSMutableAttributedString {
        let attrs: [NSAttributedString.Key: Any] = [.font: font, .foregroundColor: color]
        let string = NSMutableAttributedString(string:text, attributes: attrs)
        append(string)
        return self
    }
    
}

UIColor+Extension.swift

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0

import UIKit

extension UIColor {

    // Example usage: 
    // let someColor = UIColor(rgb: 0xFC707D)
    public convenience init(rgb: Int) {
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8)  / 255.0,
            blue: CGFloat((rgb & 0x0000FF) >> 0)  / 255.0,
            alpha: 1
        )
    }
    
    // Example usage: 
    // let someColor = UIColor(rgba: 0xEF445626)
    // Hexadecimal color code for transparency: https://gist.github.com/lopspower/03fb1cc0ac9f32ef38f4
    public convenience init(rgba: UInt64) {
        self.init(
            red: CGFloat((rgba & 0xFF000000) >> 24) / 255.0,
            green: CGFloat((rgba & 0x00FF0000) >> 16)  / 255.0,
            blue: CGFloat((rgba & 0x0000FF00) >> 8)  / 255.0,
            alpha: CGFloat((rgba & 0x000000FF) >> 0) / 255.0
        )
    }

}

UIView+Extension.swift

import UIKit

extension UIView {

    /// Adds multiple views to the end of the receiver’s list of subviews.
    /// - Parameter subviews: Collection of subviews to be added to view
    func addSubviews(_ subviews: UIView...) {
        subviews.forEach ({
            $0.translatesAutoresizingMaskIntoConstraints = false
            addSubview($0)
        })
    }
    
    /// Makes the edge constraints (`topAnchor`, `bottomAnchor`, `leadingAnchor`, `trailingAnchor`) of a view equaled to the edge constraints of another view.
    /// - Parameters:
    ///   - view: The view that we are constraining the current view's edges to.
    ///   For example : `currentView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true`
    ///   - padding: An equal amount of spacing between each edge of the current view  and `view`.
    ///   In a superview and subview relationship, `padding` is the equal space that surrounds the subview inside of the superview.
    func edges(equalTo view: UIView, padding: CGFloat = 0) {
        view.addSubview(self)
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            topAnchor.constraint(equalTo: view.topAnchor, constant: padding),
            bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -padding),
            leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: padding),
            trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -padding)
        ])
    }
    
    /// Makes the edge constraints (`topAnchor`, `bottomAnchor`, `leadingAnchor`, `trailingAnchor`) of a view equaled to the edge constraints of another view.
    /// - Parameters:
    ///   - view: The view that we are constraining the current view's edges to.
    ///   For example : `currentView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true`
    ///   - inset: Edge inset distance. Bottom and right edge inset values are multiplied by -1 for convenience.
    func edges(equalTo view: UIView, inset: UIEdgeInsets) {
        view.addSubview(self)
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            topAnchor.constraint(equalTo: view.topAnchor, constant: inset.top),
            bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -inset.bottom),
            leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: inset.left),
            trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -inset.right)
        ])
    }
    
    /// Makes the edge constraints (`topAnchor`, `bottomAnchor`, `leadingAnchor`, `trailingAnchor`) of a view equaled to the layout margins of another view.
    /// - Parameters:
    ///   - view: The view that we are constraining the current view's edges to.
    ///   For example : `currentView.topAnchor.constraint(equalTo: view.layoutMarginsGuide.topAnchor).isActive = true`
    ///   - padding: An equal amount of spacing between each edge of the current view  and `view`.
    ///   In a superview and subview relationship, `padding` is the equal space that surrounds the subview inside of the superview.
    func edges(equalToLayoutMarginIn view: UIView, padding: CGFloat = 0) {
        view.addSubview(self)
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            topAnchor.constraint(equalTo: view.layoutMarginsGuide.topAnchor, constant: padding),
            bottomAnchor.constraint(equalTo: view.layoutMarginsGuide.bottomAnchor, constant: -padding),
            leadingAnchor.constraint(equalTo: view.layoutMarginsGuide.leadingAnchor, constant: padding),
            trailingAnchor.constraint(equalTo: view.layoutMarginsGuide.trailingAnchor, constant: -padding)
        ])
    }
    
    /// Makes the edge constraints (`topAnchor`, `bottomAnchor`, `leadingAnchor`, `trailingAnchor`) of a view equaled to the safe area of another view.
    /// - Parameters:
    ///   - view: The view that we are constraining the current view's edges to.
    ///   For example : `currentView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true`
    ///   - padding: An equal amount of spacing between each edge of the current view  and `view`.
    ///   In a superview and subview relationship, `padding` is the equal space that surrounds the subview inside of the superview.
    func edges(equalToSafeAreaIn view: UIView, padding: CGFloat = 0) {
        view.addSubview(self)
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: padding),
            bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -padding),
            leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: padding),
            trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -padding)
        ])
    }
    
    /// Makes the center x and y anchors of a view equaled to the center x and y anchors of another view.
    /// - Parameter view: The view that we're constraining the current view's center anchors to.
    /// For example : `currentView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true`
    func center(equalTo view: UIView) {
        view.addSubview(self)
        translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            centerXAnchor.constraint(equalTo: view.centerXAnchor),
            centerYAnchor.constraint(equalTo: view.centerYAnchor)
        ])
    }
    
    /// Adds corner radius to specified corners. If no corners are specified, adds corner radius to all corners.
    /// - Parameters:
    ///   - cornerRadius: The radius to use when drawing rounded corners for the layer’s background.
    ///   - corners: Array of corners that will to apply corner radius. Passing `nil` or an empty array will add corner radius to all corners. Function will ignore reference to `UIRectCorner.allCorners`.
    func cornerRadius(_ cornerRadius: CGFloat, corners: [UIRectCorner]? = nil) {
        guard let corners = corners, !corners.isEmpty else {
            layer.cornerRadius = cornerRadius
            return
        }
        
        var maskedCorners: CACornerMask = []
        
        for corner in corners {
            switch corner {
            case .topLeft:
                maskedCorners.update(with: .layerMinXMinYCorner)
            case .topRight:
                maskedCorners.update(with: .layerMaxXMinYCorner)
            case .bottomLeft:
                maskedCorners.update(with: .layerMinXMaxYCorner)
            case .bottomRight:
                maskedCorners.update(with: .layerMaxXMaxYCorner)
            default:
                continue
            }
        }
        
        layer.cornerRadius = cornerRadius
        layer.maskedCorners = maskedCorners
    }
    
}