Spinner for iOS Swift

Spinner.swift

//
//  Spinner.swift
//
//  Created by RJ John Patrick Cruz on 1/22/16.
//  Copyright © 2016 RJ John Patrick Cruz. All rights reserved.
//

import Foundation
import UIKit

class MyView : UIView {
    override func drawRect(rect: CGRect) {
    }
}

public class Spinner:UIView {
    
    let utilities = Utilities()
    
    public static let sharedInstance = Spinner()
    
    public let activityIndicator = UIActivityIndicatorView()
    public let viewContainer = UIView()
    
    public var isVisible = false
    
    private let kNavigationBarHeight:CGFloat = 44.0
    
    public class func show(canvas: UIView) {
        self.sharedInstance.showActivityIndicator(canvas, true)
    }
    
    public class func show(canvas: UIView, _ hasNavigationBar: Bool) {
        self.sharedInstance.showActivityIndicator(canvas, hasNavigationBar)
    }
    
    public class func hide() {
        self.sharedInstance.hideActivityIndicator()
    }
    
    func showActivityIndicator(canvas: UIView, _ hasNavigationBar: Bool) {
        
        self.isVisible = true
        
        let window = UIApplication.sharedApplication().windows.first!
        
        self.viewContainer.backgroundColor = utilities.getHexColor(0x737575).colorWithAlphaComponent(0.4)
        self.viewContainer.frame = canvas.bounds
        
        let superview = UIView(frame: CGRectMake(window.bounds.midX - 79, window.bounds.midY - 70, 0, 0))
        
        let shadowView = UIView(frame: CGRectMake(50, 50, 60, 60))
        shadowView.layer.shadowColor = UIColor.blackColor().CGColor
        shadowView.layer.shadowOffset = CGSizeZero
        shadowView.layer.shadowOpacity = 0.5
        shadowView.layer.shadowRadius = 5
        
        let view = MyView(frame: shadowView.bounds)
        view.backgroundColor = UIColor.grayColor()
        view.layer.cornerRadius = 10.0
        view.layer.borderColor = UIColor.grayColor().CGColor
        view.layer.borderWidth = 0.5
        view.clipsToBounds = true
        
        self.activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray
        self.activityIndicator.center = CGPointMake(view.bounds.size.width / 2.0, (view.bounds.size.height / 2.0) - (hasNavigationBar ? kNavigationBarHeight : 0));
        self.activityIndicator.activityIndicatorViewStyle = .WhiteLarge
        self.activityIndicator.startAnimating()
        
        view.addSubview(self.activityIndicator)
        shadowView.addSubview(view)
        superview.addSubview(shadowView)
        
        self.viewContainer.addSubview(superview)
        canvas.addSubview(self.viewContainer)
        
    }
    
    func hideActivityIndicator() {
        
        UIView.animateWithDuration(0.15, delay: 0, options: (UIViewAnimationOptions.CurveEaseIn), animations: { () -> Void in
            self.alpha = 0
            }) { (finished) -> Void in
                self.viewContainer.removeFromSuperview()
                
                self.isVisible = false;
        }
    }
}