Cache Image Locally

ImageCacheHelper.swift

//
//  UIImageExtension.swift
//  EddyCab
//
//  Created by Anish on 1/4/16.
//  Copyright © 2016 Esig. All rights reserved.
//

import Foundation
import Alamofire
import SwiftyJSON

class ImageCacheHelper:NSObject{

    static var cache = NSCache()
    static var isNotRunningDispatch:Bool = true
    
   class func setObjectForKey(imageData:NSData,imageKey:String){
        
       
        ImageCacheHelper.cache.setObject(imageData, forKey: imageKey)
      
    }
    
    class func getObjectForKey(imageKey:String)->NSData?{
    

        return ImageCacheHelper.cache.objectForKey(imageKey) as? NSData
    
    }
    

    class func getImage(imageUrl:String,completionHandler:(NSData)->()){
        
        
        if ImageCacheHelper.isNotRunningDispatch{
            
            ImageCacheHelper.isNotRunningDispatch = false
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), {
                
                let imgUrl = NSURL(string:imageUrl)
                let imageData = NSData(contentsOfURL: imgUrl!)!
                ImageCacheHelper.setObjectForKey(imageData, imageKey: "\(imageUrl.hashValue)")
                ImageCacheHelper.isNotRunningDispatch = true
                completionHandler(imageData)
                
            })
        
        }else{
        
            print("alerady started loading image")
        
        }
    }
  
}

//how you call this class is as 
let userImageUrl = "\(appUrl)\(imageUrlString)"
let fileManager = NSFileManager.defaultManager()
let diskPaths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.CachesDirectory, NSSearchPathDomainMask.UserDomainMask, true)
let cacheDirectory = diskPaths[0] as NSString
let diskPath = cacheDirectory.stringByAppendingPathComponent("\(userImageUrl.hashValue)")
if let data = ImageCacheHelper.getObjectForKey("\(userImageUrl.hashValue)"){
          let userImage =  UIImage(data: data)
          self.userImgView.image = userImage
                        
}else if fileManager.fileExistsAtPath(diskPath){
                        
          let image =  UIImage(contentsOfFile: diskPath)
          self.userImgView.image = image
          ImageCacheHelper.setObjectForKey(UIImageJPEGRepresentation(image, 1.0)!, imageKey: "\(userImageUrl.hashValue)")
                        
}else{
          ImageCacheHelper.getImage(userImageUrl){ imageData in
                            
            imageData.writeToFile(diskPath, atomically: true)
                    dispatch_async(dispatch_get_main_queue()){
                                
                        let userImage =  UIImage(data: imageData)
                        self.userImgView.image = userImage
                                
                    }
            }
                        
}