Random utilities in UIKit Swift

utilities.swift

import Foundation
import UIKit

extension UIColor {
    convenience init(colorArray array: [CGFloat]) {
        let r = array[0]
        let g = array[1]
        let b = array[2]
        self.init(red: r/255.0, green: g/255.0, blue: b/255.0, alpha:1.0)
    }
}

extension UIImage {
    public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
        let rect = CGRect(origin: .zero, size: size)
        UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
        color.setFill()
        UIRectFill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        guard let cgImage = image?.cgImage else { return nil }
        self.init(cgImage: cgImage)
    }
    
    func filledImage(fillColor: UIColor) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.size, false, UIScreen.main.scale)
        
        let context = UIGraphicsGetCurrentContext()!
        fillColor.setFill()
        
        context.translateBy(x: 0, y: self.size.height)
        context.scaleBy(x: 1.0, y: -1.0)
        
        context.setBlendMode(CGBlendMode.colorBurn)
        
        let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height)
        context.draw(self.cgImage!, in: rect)
        
        context.setBlendMode(CGBlendMode.sourceIn)
        context.addRect(rect)
        context.drawPath(using: CGPathDrawingMode.fill)
        
        let coloredImg : UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        
        return coloredImg
    }
}
extension UITextField {
    
    func useUnderline(_ color: UIColor) {
        let border = CALayer()
        let borderWidth = CGFloat(1.0)
        border.borderColor = color.cgColor
        border.frame = CGRect(x: 0, y: self.frame.size.height - borderWidth, width: self.frame.size.width, height: self.frame.size.height)
        border.borderWidth = borderWidth
        self.layer.addSublayer(border)
        self.layer.masksToBounds = true
    }
}

extension UIView {
    func applyGradient(colours: [UIColor]) -> Void {
        self.applyGradient(colours: colours, locations: nil)
    }
    
    func applyGradient(colours: [UIColor], locations: [NSNumber]?) -> Void {
        let gradient: CAGradientLayer = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = colours.map { $0.cgColor }
        gradient.locations = locations
        self.layer.insertSublayer(gradient, at: 0)
    }
}

extension String {
    static func isBlank(_ optionalString :String?) -> Bool {
        if let string = optionalString {
            return string.isEmpty
        } else {
            return true
        }
    }
    
    func convertToJSONObject() -> [String: Any]? {
        if let data = self.data(using: .utf8) {
            do {
                return try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
            } catch {
                print(error.localizedDescription)
            }
        }
        return nil
    }
}

public extension Sequence {
    func categorise<U : Hashable>(_ key: (Iterator.Element) -> U) -> [U:[Iterator.Element]] {
        var dict: [U:[Iterator.Element]] = [:]
        for el in self {
            let key = key(el)
            if case nil = dict[key]?.append(el) { dict[key] = [el] }
        }
        return dict
    }
}

extension UIButton {
    func setBackgroundColor(_ color: UIColor, for state: UIControlState) {
        self.setBackgroundImage(UIImage(color: color), for: state)
    }
}