Can someone explain how this image caching code works? I understand a task is being done to download the contents of the imageURL, checks to if error are present and displays it on the main thread. But what is the use of forKey: url.absoluteString as NSString?
func downloadImage(from urlString: String ) {
guard let url = URL(string: urlString) else { return }
storeCache(url: url)
}
func storeCache(url:URL){
if let cachedImage = imageCache.object(forKey: url.absoluteString as NSString) as? UIImage {
self.image = cachedImage
}else {
let _: Void = URLSession.shared.dataTask(with: url) { [weak self] data, response, error in
guard let self = self else { return }
if error != nil { return }
DispatchQueue.main.async {
if let downloadedImage = UIImage(data: data!) {
imageCache.setObject(downloadedImage, forKey: url.absoluteString as NSString)
self.image = downloadedImage
}
}
}.resume()
}
}
Your cache is basically a fancy [url: image] dictionary. It allows the device to request once and then remember images until the app is closed.
Every time you need an image, your app will check the cache, just like a dictionary and ask if there's already a downloaded image from that url.
if let cachedImage = imageCache.object(forKey: url.absoluteString... // empty
Of course, when they first run the app, the cache will be empty. So it grabs the image from the internet and stores it in the cache, remembering which url it came from.
imageCache.setObject(downloadedImage, forKey: url.absoluteString... // cache the image
From now on whenever it needs an image from that same url, it will check the cache and see you've already downloaded it. No more requests.
if let cachedImage = imageCache.object(forKey: url.absoluteString... // something there!
Related
In Swift 3, I am trying to capture an image from the internet, and have these lines of code:
var catPictureURL = NSURL(fileURLWithPath: "http://i.imgur.com/w5rkSIj.jpg")
var catPictureData = NSData(contentsOf: catPictureURL as URL) // nil
var catPicture = UIImage(data: catPictureData as! Data)
What am I doing wrong here?
There's a few things with your code as it stands:
You are using a lot of casting, which is not needed.
You are treating your URL as a local file URL, which is not the case.
You are never downloading the URL to be used by your image.
The first thing we are going to do is to declare your variable as let, as we are not going to modify it later.
let catPictureURL = URL(string: "http://i.imgur.com/w5rkSIj.jpg")! // We can force unwrap because we are 100% certain the constructor will not return nil in this case.
Then we need to download the contents of that URL. We can do this with the URLSession object. When the completion handler is called, we will have a UIImage downloaded from the web.
// Creating a session object with the default configuration.
// You can read more about it here https://developer.apple.com/reference/foundation/urlsessionconfiguration
let session = URLSession(configuration: .default)
// Define a download task. The download task will download the contents of the URL as a Data object and then you can do what you wish with that data.
let downloadPicTask = session.dataTask(with: catPictureURL) { (data, response, error) in
// The download has finished.
if let e = error {
print("Error downloading cat picture: \(e)")
} else {
// No errors found.
// It would be weird if we didn't have a response, so check for that too.
if let res = response as? HTTPURLResponse {
print("Downloaded cat picture with response code \(res.statusCode)")
if let imageData = data {
// Finally convert that Data into an image and do what you wish with it.
let image = UIImage(data: imageData)
// Do something with your image.
} else {
print("Couldn't get image: Image is nil")
}
} else {
print("Couldn't get response code for some reason")
}
}
}
Finally you need to call resume on the download task, otherwise your task will never start:
downloadPicTask.resume().
All this code may look a bit intimidating at first, but the URLSession APIs are block based so they can work asynchronously - If you block your UI thread for a few seconds, the OS will kill your app.
Your full code should look like this:
let catPictureURL = URL(string: "http://i.imgur.com/w5rkSIj.jpg")!
// Creating a session object with the default configuration.
// You can read more about it here https://developer.apple.com/reference/foundation/urlsessionconfiguration
let session = URLSession(configuration: .default)
// Define a download task. The download task will download the contents of the URL as a Data object and then you can do what you wish with that data.
let downloadPicTask = session.dataTask(with: catPictureURL) { (data, response, error) in
// The download has finished.
if let e = error {
print("Error downloading cat picture: \(e)")
} else {
// No errors found.
// It would be weird if we didn't have a response, so check for that too.
if let res = response as? HTTPURLResponse {
print("Downloaded cat picture with response code \(res.statusCode)")
if let imageData = data {
// Finally convert that Data into an image and do what you wish with it.
let image = UIImage(data: imageData)
// Do something with your image.
} else {
print("Couldn't get image: Image is nil")
}
} else {
print("Couldn't get response code for some reason")
}
}
}
downloadPicTask.resume()
let url = URL(string: "http://i.imgur.com/w5rkSIj.jpg")
let data = try? Data(contentsOf: url)
if let imageData = data {
let image = UIImage(data: imageData)
}
Swift
Good solution to extend native functionality by extensions
import UIKit
extension UIImage {
convenience init?(url: URL?) {
guard let url = url else { return nil }
do {
self.init(data: try Data(contentsOf: url))
} catch {
print("Cannot load image from url: \(url) with error: \(error)")
return nil
}
}
}
Usage
Convenience initializer is failable and accepts optional URL – approach is safe.
imageView.image = UIImage(url: URL(string: "some_url.png"))
You could also use Alamofire\AlmofireImage for that task:
https://github.com/Alamofire/AlamofireImage
The code should look something like that (Based on the first example on link above):
import AlamofireImage
Alamofire.request("http://i.imgur.com/w5rkSIj.jpg").responseImage { response in
if let catPicture = response.result.value {
print("image downloaded: \(image)")
}
}
While it is neat yet safe, you should consider if that worth the Pod overhead.
If you are going to use more images and would like to add also filter and transiations I would consider using AlamofireImage
Use this extension and download image faster.
extension UIImageView {
public func imageFromURL(urlString: String) {
let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
activityIndicator.frame = CGRect.init(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height)
activityIndicator.startAnimating()
if self.image == nil{
self.addSubview(activityIndicator)
}
URLSession.shared.dataTask(with: NSURL(string: urlString)! as URL, completionHandler: { (data, response, error) -> Void in
if error != nil {
print(error ?? "No Error")
return
}
DispatchQueue.main.async(execute: { () -> Void in
let image = UIImage(data: data!)
activityIndicator.removeFromSuperview()
self.image = image
})
}).resume()
}
}
Using Alamofire worked out for me on Swift 3:
Step 1:
Integrate using pods.
pod 'Alamofire', '~> 4.4'
pod 'AlamofireImage', '~> 3.3'
Step 2:
import AlamofireImage
import Alamofire
Step 3:
Alamofire.request("https://httpbin.org/image/png").responseImage { response in
if let image = response.result.value {
print("image downloaded: \(image)")
self.myImageview.image = image
}
}
The easiest way according to me will be using SDWebImage
Add this to your pod file
pod 'SDWebImage', '~> 4.0'
Run pod install
Now import SDWebImage
import SDWebImage
Now for setting image from url
imageView.sd_setImage(with: URL(string: "http://www.domain/path/to/image.jpg"), placeholderImage: UIImage(named: "placeholder.png"))
It will show placeholder image but when image is downloaded it will show the image from url .Your app will never crash
This are the main feature of SDWebImage
Categories for UIImageView, UIButton, MKAnnotationView adding web image and cache management
An asynchronous image downloader
An asynchronous memory + disk image caching with automatic cache expiration handling
A background image decompression
A guarantee that the same URL won't be downloaded several times
A guarantee that bogus URLs won't be retried again and again
A guarantee that main thread will never be blocked
Performances!
Use GCD and ARC
To know more https://github.com/rs/SDWebImage
Use extension for UIImageView to Load URL Images.
let imageCache = NSCache<NSString, UIImage>()
extension UIImageView {
func imageURLLoad(url: URL) {
DispatchQueue.global().async { [weak self] in
func setImage(image:UIImage?) {
DispatchQueue.main.async {
self?.image = image
}
}
let urlToString = url.absoluteString as NSString
if let cachedImage = imageCache.object(forKey: urlToString) {
setImage(image: cachedImage)
} else if let data = try? Data(contentsOf: url), let image = UIImage(data: data) {
DispatchQueue.main.async {
imageCache.setObject(image, forKey: urlToString)
setImage(image: image)
}
}else {
setImage(image: nil)
}
}
}
}
We are able to fetch image directly without using Third Party SDK like 'AlamofireImage', 'Kingfisher' and 'SDWebImage'
Swift 5
DispatchQueue.global(qos: .background).async {
do{
let data = try Data.init(contentsOf: URL.init(string:"url")!)
DispatchQueue.main.async {
let image: UIImage? = UIImage(data: data)
yourImageView.image = image
}
}
catch let errorLog {
debugPrint(errorLog.localizedDescription)
}
}
let url = ("https://firebasestorage.googleapis.com/v0/b/qualityaudit-678a4.appspot.com/o/profile_images%2FBFA28EDD-9E15-4CC3-9AF8-496B91E74A11.png?alt=media&token=b4518b07-2147-48e5-93fb-3de2b768412d")
self.myactivityindecator.startAnimating()
let urlString = url
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url)
{
(data, response, error) in
if error != nil {
print("Failed fetching image:", error!)
return
}
guard let response = response as? HTTPURLResponse, response.statusCode == 200 else {
print("error")
return
}
DispatchQueue.main.async {
let image = UIImage(data: data!)
let myimageview = UIImageView(image: image)
print(myimageview)
self.imgdata.image = myimageview.image
self.myactivityindecator.stopanimating()
}
}.resume()
I use AlamofireImage it works fine for me for Loading url within ImageView, which also has Placeholder option.
func setImage (){
let image = “https : //i.imgur.com/w5rkSIj.jpg”
if let url = URL (string: image)
{
//Placeholder Image which was in your Local(Assets)
let image = UIImage (named: “PlacehoderImageName”)
imageViewName.af_setImage (withURL: url, placeholderImage: image)
}
}
Note:- Dont forget to Add AlamofireImage in your Pod file as well as in Import Statment
Say Example,
pod 'AlamofireImage' within Your PodFile and in ViewController import AlamofireImage
I have UIImageView and I want to download images in cache if exist, I've used extension func.
I have this code but not working:
extension UIImageView {
func loadImageUsingCache (_ urlString : String) {
let imageCache = NSCache<AnyObject, AnyObject>()
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
let url = URL(string: urlString)
URLSession.shared.dataTask(with: url!) { (data, response, error) in
if data != nil {
if let image = UIImage(data: data!) {
imageCache.setObject(image, forKey: urlString as AnyObject)
DispatchQueue.main.async(execute: {
self.image = image
})
}
}
}.resume()
}
}
You're creating the new NSCache object for each image and not retain it.
You should create object variable instead of local one. It won't work in extension in this case. Also you can try to use URLCache.shared instead.
// It's Perfect Solution //
var imageCache = String: UIImage
class CustomImageView: UIImageView {
var lastImgUrlUsedToLoadImage: String?
func loadImage(with urlString: String) {
// set image to nil
self.image = nil
// set lastImgUrlUsedToLoadImage
lastImgUrlUsedToLoadImage = urlString
// check if image exists in cache
if let cachedImage = imageCache[urlString] {
self.image = cachedImage
return
}
// url for image location
guard let url = URL(string: urlString) else { return }
// fetch contents of URL
URLSession.shared.dataTask(with: url) { (data, response, error) in
// handle error
if let error = error {
print("Failed to load image with error", error.localizedDescription)
}
if self.lastImgUrlUsedToLoadImage != url.absoluteString {
return
}
// image data
guard let imageData = data else { return }
// create image using image data
let photoImage = UIImage(data: imageData)
// set key and value for image cache
imageCache[url.absoluteString] = photoImage
// set image
DispatchQueue.main.async {
self.image = photoImage
}
}.resume()
}
}
I have a function that is loading a pic of the user from URL that is using this UIImageView extension:
let imageCache = NSCache<AnyObject, AnyObject>()
extension UIImageView {
func loadImageUsingCacheWithUrlString(urlString: String) {
self.image = nil
print("here the URL of the image", urlString)
//check cache for image first
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
// otherwise fire off a new download
let url = URL(string: urlString)
URLSession.shared.dataTask(with: url!, completionHandler: { (data, response, error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.async {
if let downloadedImage = UIImage(data: data!) {
imageCache.setObject(downloadedImage, forKey: urlString as AnyObject)
self.image = downloadedImage
}
}
}).resume()
}
}
Now, the problem I have is, that sometimes the the profile picture is loaded and sometimes not. I suppose that this happen because the function download the image asynchronously, but why once it's downloaded it doesn't appear On the profile?
I'm calling it with:
if hostPerfil != nil {
if let photo = hostPerfil?.picture {
hostPic.loadImageUsingCacheWithUrlString(urlString: photo)
}
hostName.text = hostPerfil!.firstName
}
What am I doing wrong? Can anyone help me with this, please?
When you get the image from your imageCache, you need to set the image of the UIImageView within the main UI thread so that it will be rendered properly. You did that when you download it, that is why it is displaying, but you have to do it as well when you are getting it from cache.
DispatchQueue.main.async {
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
}
I want to display avatar image in my table view cell by the url string. and it will crash when the phone is not connect to the internet, so I added Reachability swift to it. but now I face another problem, when the user leaving the wifi zone or the internet connection is not stable, the app will freeze, I'm not able to tap anything until I walk back the strong wifi zone. why?
let imageData:NSData = try! NSData(contentsOf: imageUrl)
this code will crash so I try add do & catch but still not working. is it because the app can't connect to the url string and get the data so that the app will be freeze? how to prevent an app crash or freeze due to a slow connection when retrieving a remote photo?
if Reachability.shared.isConnectedToNetwork(){
if let crew = user!["crew"] as? [String:Any], let crewAva = crew["crew_avatar"] as? String {
let imageUrlString = crewAva
let imageUrl:URL = URL(string: imageUrlString)!
DispatchQueue.main.async(execute: {
do{
let imageData:NSData = try NSData(contentsOf: imageUrl)
let image = UIImage(data: imageData as Data)
self.avaImg.image = image
}
catch{
print("error")
}
})
}
}else{
print("Not reachable")
}
From the NSData documentation:
init?(contentsOf url: URL)
Important
Don't use this synchronous method to request network-based URLs. For network-based URLs, this method can block the current thread for tens of seconds on a slow network, resulting in a poor user experience, and in iOS, may cause your app to be terminated.
Instead, for non-file URLs, consider using the dataTask(with:completionHandler:) method of the NSURLSession class. See URL Session Programming Guide for details.
Solution
func getDataFromUrl(url: URL, completion: #escaping (Data?, URLResponse?, Error?) -> ()) {
URLSession.shared.dataTask(with: url) { data, response, error in
completion(data, response, error)
}.resume()
}
func downloadImage(url: URL) {
getDataFromUrl(url: url) { data, response, error in
guard let data = data, error == nil else { return }
print(response?.suggestedFilename ?? url.lastPathComponent)
DispatchQueue.main.async() {
self.avaImg.image = UIImage(data: data)
}
}
}
override func viewWillAppear(_ animated: Bool) {
if let crew = user!["crew"] as? [String:Any], let crewAva = crew["crew_avatar"] as? String {
let imageUrlString = crewAva
let url = URL(string: imageUrlString)!
downloadImage(url: url)
}
}
Try only updating the UI on the main thread.
if Reachability.shared.isConnectedToNetwork(){
if let crew = user!["crew"] as? [String:Any], let crewAva = crew["crew_avatar"] as? String {
let imageUrlString = crewAva
let imageUrl:URL = URL(string: imageUrlString)!
let imageData:NSData = try NSData(contentsOf: imageUrl)
let image = UIImage(data: imageData as Data)
DispatchQueue.main.async(execute: {
do{
self.avaImg.image = image
}
catch{
print("error")
}
})
}
}else{
print("Not reachable")
}
In Swift 3, I am trying to capture an image from the internet, and have these lines of code:
var catPictureURL = NSURL(fileURLWithPath: "http://i.imgur.com/w5rkSIj.jpg")
var catPictureData = NSData(contentsOf: catPictureURL as URL) // nil
var catPicture = UIImage(data: catPictureData as! Data)
What am I doing wrong here?
There's a few things with your code as it stands:
You are using a lot of casting, which is not needed.
You are treating your URL as a local file URL, which is not the case.
You are never downloading the URL to be used by your image.
The first thing we are going to do is to declare your variable as let, as we are not going to modify it later.
let catPictureURL = URL(string: "http://i.imgur.com/w5rkSIj.jpg")! // We can force unwrap because we are 100% certain the constructor will not return nil in this case.
Then we need to download the contents of that URL. We can do this with the URLSession object. When the completion handler is called, we will have a UIImage downloaded from the web.
// Creating a session object with the default configuration.
// You can read more about it here https://developer.apple.com/reference/foundation/urlsessionconfiguration
let session = URLSession(configuration: .default)
// Define a download task. The download task will download the contents of the URL as a Data object and then you can do what you wish with that data.
let downloadPicTask = session.dataTask(with: catPictureURL) { (data, response, error) in
// The download has finished.
if let e = error {
print("Error downloading cat picture: \(e)")
} else {
// No errors found.
// It would be weird if we didn't have a response, so check for that too.
if let res = response as? HTTPURLResponse {
print("Downloaded cat picture with response code \(res.statusCode)")
if let imageData = data {
// Finally convert that Data into an image and do what you wish with it.
let image = UIImage(data: imageData)
// Do something with your image.
} else {
print("Couldn't get image: Image is nil")
}
} else {
print("Couldn't get response code for some reason")
}
}
}
Finally you need to call resume on the download task, otherwise your task will never start:
downloadPicTask.resume().
All this code may look a bit intimidating at first, but the URLSession APIs are block based so they can work asynchronously - If you block your UI thread for a few seconds, the OS will kill your app.
Your full code should look like this:
let catPictureURL = URL(string: "http://i.imgur.com/w5rkSIj.jpg")!
// Creating a session object with the default configuration.
// You can read more about it here https://developer.apple.com/reference/foundation/urlsessionconfiguration
let session = URLSession(configuration: .default)
// Define a download task. The download task will download the contents of the URL as a Data object and then you can do what you wish with that data.
let downloadPicTask = session.dataTask(with: catPictureURL) { (data, response, error) in
// The download has finished.
if let e = error {
print("Error downloading cat picture: \(e)")
} else {
// No errors found.
// It would be weird if we didn't have a response, so check for that too.
if let res = response as? HTTPURLResponse {
print("Downloaded cat picture with response code \(res.statusCode)")
if let imageData = data {
// Finally convert that Data into an image and do what you wish with it.
let image = UIImage(data: imageData)
// Do something with your image.
} else {
print("Couldn't get image: Image is nil")
}
} else {
print("Couldn't get response code for some reason")
}
}
}
downloadPicTask.resume()
let url = URL(string: "http://i.imgur.com/w5rkSIj.jpg")
let data = try? Data(contentsOf: url)
if let imageData = data {
let image = UIImage(data: imageData)
}
Swift
Good solution to extend native functionality by extensions
import UIKit
extension UIImage {
convenience init?(url: URL?) {
guard let url = url else { return nil }
do {
self.init(data: try Data(contentsOf: url))
} catch {
print("Cannot load image from url: \(url) with error: \(error)")
return nil
}
}
}
Usage
Convenience initializer is failable and accepts optional URL – approach is safe.
imageView.image = UIImage(url: URL(string: "some_url.png"))
You could also use Alamofire\AlmofireImage for that task:
https://github.com/Alamofire/AlamofireImage
The code should look something like that (Based on the first example on link above):
import AlamofireImage
Alamofire.request("http://i.imgur.com/w5rkSIj.jpg").responseImage { response in
if let catPicture = response.result.value {
print("image downloaded: \(image)")
}
}
While it is neat yet safe, you should consider if that worth the Pod overhead.
If you are going to use more images and would like to add also filter and transiations I would consider using AlamofireImage
Use this extension and download image faster.
extension UIImageView {
public func imageFromURL(urlString: String) {
let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
activityIndicator.frame = CGRect.init(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height)
activityIndicator.startAnimating()
if self.image == nil{
self.addSubview(activityIndicator)
}
URLSession.shared.dataTask(with: NSURL(string: urlString)! as URL, completionHandler: { (data, response, error) -> Void in
if error != nil {
print(error ?? "No Error")
return
}
DispatchQueue.main.async(execute: { () -> Void in
let image = UIImage(data: data!)
activityIndicator.removeFromSuperview()
self.image = image
})
}).resume()
}
}
Using Alamofire worked out for me on Swift 3:
Step 1:
Integrate using pods.
pod 'Alamofire', '~> 4.4'
pod 'AlamofireImage', '~> 3.3'
Step 2:
import AlamofireImage
import Alamofire
Step 3:
Alamofire.request("https://httpbin.org/image/png").responseImage { response in
if let image = response.result.value {
print("image downloaded: \(image)")
self.myImageview.image = image
}
}
The easiest way according to me will be using SDWebImage
Add this to your pod file
pod 'SDWebImage', '~> 4.0'
Run pod install
Now import SDWebImage
import SDWebImage
Now for setting image from url
imageView.sd_setImage(with: URL(string: "http://www.domain/path/to/image.jpg"), placeholderImage: UIImage(named: "placeholder.png"))
It will show placeholder image but when image is downloaded it will show the image from url .Your app will never crash
This are the main feature of SDWebImage
Categories for UIImageView, UIButton, MKAnnotationView adding web image and cache management
An asynchronous image downloader
An asynchronous memory + disk image caching with automatic cache expiration handling
A background image decompression
A guarantee that the same URL won't be downloaded several times
A guarantee that bogus URLs won't be retried again and again
A guarantee that main thread will never be blocked
Performances!
Use GCD and ARC
To know more https://github.com/rs/SDWebImage
Use extension for UIImageView to Load URL Images.
let imageCache = NSCache<NSString, UIImage>()
extension UIImageView {
func imageURLLoad(url: URL) {
DispatchQueue.global().async { [weak self] in
func setImage(image:UIImage?) {
DispatchQueue.main.async {
self?.image = image
}
}
let urlToString = url.absoluteString as NSString
if let cachedImage = imageCache.object(forKey: urlToString) {
setImage(image: cachedImage)
} else if let data = try? Data(contentsOf: url), let image = UIImage(data: data) {
DispatchQueue.main.async {
imageCache.setObject(image, forKey: urlToString)
setImage(image: image)
}
}else {
setImage(image: nil)
}
}
}
}
We are able to fetch image directly without using Third Party SDK like 'AlamofireImage', 'Kingfisher' and 'SDWebImage'
Swift 5
DispatchQueue.global(qos: .background).async {
do{
let data = try Data.init(contentsOf: URL.init(string:"url")!)
DispatchQueue.main.async {
let image: UIImage? = UIImage(data: data)
yourImageView.image = image
}
}
catch let errorLog {
debugPrint(errorLog.localizedDescription)
}
}
let url = ("https://firebasestorage.googleapis.com/v0/b/qualityaudit-678a4.appspot.com/o/profile_images%2FBFA28EDD-9E15-4CC3-9AF8-496B91E74A11.png?alt=media&token=b4518b07-2147-48e5-93fb-3de2b768412d")
self.myactivityindecator.startAnimating()
let urlString = url
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url)
{
(data, response, error) in
if error != nil {
print("Failed fetching image:", error!)
return
}
guard let response = response as? HTTPURLResponse, response.statusCode == 200 else {
print("error")
return
}
DispatchQueue.main.async {
let image = UIImage(data: data!)
let myimageview = UIImageView(image: image)
print(myimageview)
self.imgdata.image = myimageview.image
self.myactivityindecator.stopanimating()
}
}.resume()
I use AlamofireImage it works fine for me for Loading url within ImageView, which also has Placeholder option.
func setImage (){
let image = “https : //i.imgur.com/w5rkSIj.jpg”
if let url = URL (string: image)
{
//Placeholder Image which was in your Local(Assets)
let image = UIImage (named: “PlacehoderImageName”)
imageViewName.af_setImage (withURL: url, placeholderImage: image)
}
}
Note:- Dont forget to Add AlamofireImage in your Pod file as well as in Import Statment
Say Example,
pod 'AlamofireImage' within Your PodFile and in ViewController import AlamofireImage