Show UIActivityIndicatorView inside UIImageView

swift

//
//  UIImageViewExtention.swift
//  MealSpecials
//
//  Created by Aruna on 8/9/15.
//  Copyright (c) 2015 com.mealspecials. All rights reserved.
//

import Foundation
import UIKit
import ObjectiveC

private var activityIndicatorAssociationKey: UInt8 = 0

extension UIImageView {
    var activityIndicator: UIActivityIndicatorView! {
        get {
            return objc_getAssociatedObject(self, &activityIndicatorAssociationKey) as? UIActivityIndicatorView
        }
        set(newValue) {
            objc_setAssociatedObject(self, &activityIndicatorAssociationKey, newValue, UInt(OBJC_ASSOCIATION_RETAIN))
        }
    }
    
    func showActivityIndicator() {

        if (self.activityIndicator == nil) {
            self.activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.Gray)

            self.activityIndicator.hidesWhenStopped = true
            self.activityIndicator.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
            self.activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.WhiteLarge
            self.activityIndicator.center = CGPointMake(self.frame.size.width / 2, self.frame.size.height / 2);
            self.activityIndicator.autoresizingMask = .FlexibleLeftMargin | .FlexibleRightMargin | .FlexibleTopMargin | .FlexibleBottomMargin
            self.activityIndicator.userInteractionEnabled = false
            
            NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in
                self.addSubview(self.activityIndicator)
                self.activityIndicator.startAnimating()
            })
        }
    }
    
    
    func hideActivityIndicator() {
        NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in
            self.activityIndicator.stopAnimating()
        })
    }
}

How to i implement this on a UICollectionView cell with UIImageView when loading data with from a server using URLSession ?

you should use kingfisher pod to get to know that you got the response from API. Before parsing the response to views implement show indicator and after parsing call hideIndicator