Building an iOS Photo Search App with Pixabay API, Alamofire, and SDWebImage

In this tutorial, we’ll walk through the steps to create a demo app that retrieves photos from Pixabay based on search text and displays them in a UICollectionView. We’ll also cover how to integrate third-party libraries using CocoaPods.

Pixabay API

First, register your app with Pixabay and obtain an API key. You’ll need this key to access the Pixabay Photo Search API.

Project Setup

1. Create a new project by selecting the Single View Application template and choosing Swift as the language.
2. We’ll use CocoaPods to install third-party libraries. Make sure CocoaPods is installed on your Mac.
3. In a terminal window, navigate to your project folder and create a file named Podfile. Add the following content:

rubyCopyuse_frameworks!
pod 'Alamofire'
pod 'SwiftyJSON'
pod 'SDWebImage'

4. Run pod install in the terminal. This will install the required libraries and create the necessary workspace.
5. Open <Project Name>.xcworkspace to add functionality to the project.

Model Class

Create a new file named Photo.swift to store photo details:

import SwiftyJSON

struct Photo {
    let id: Int
    let pageURL: String
    let previewURL: String
    let largeImageURL: String
    
    init(json: JSON) {
        id = json["id"].intValue
        pageURL = json["pageURL"].stringValue
        previewURL = json["previewURL"].stringValue
        largeImageURL = json["largeImageURL"].stringValue
    }
}

Web Service Integration

Create a new file named Services.swift and add the following code:

import Alamofire
import SwiftyJSON

protocol PixabayPhotoDownloadDelegate: AnyObject {
    func finishedDownloading(photos: [Photo])
}

class Services {
    let API_KEY = "YOUR_PIXABAY_API_KEY"
    let URL = "https://pixabay.com/api/"
    
    weak var delegate: PixabayPhotoDownloadDelegate?
    
    func makeServiceCall(searchText: String) {
        let parameters: [String: Any] = [
            "key": API_KEY,
            "q": searchText,
            "per_page": 30
        ]
        
        AF.request(URL, method: .get, parameters: parameters).responseJSON { response in
            switch response.result {
            case .success(let value):
                let json = JSON(value)
                let photos = json["hits"].arrayValue.map { Photo(json: $0) }
                self.delegate?.finishedDownloading(photos: photos)
            case .failure(let error):
                print("Request failed with error: \(error)")
            }
        }
    }
}

Design User Intrerfaces

Navigate to Main.storyboard, add a UICollectionView and UISearchBar to the ViewController as shown in the below screenshot.

In Main.storyboard, add a UICollectionView and UISearchBar to the ViewController.Add Auto Layout constraints to ensure the UI looks good on both iPad and iPhone.Add a UIImageView to the CollectionViewCell.Embed the ViewController in a Navigation Controller.Add a second View Controller to act as the Detail View Controller for displaying selected photos. If you need help with Auto Layout then check out this tutorial.

Add Custom Cell

Create a new file named PhotoCell.swift:

import UIKit

class PhotoCell: UICollectionViewCell {
    @IBOutlet weak var imageView: UIImageView!
}

Set this class as the Custom Class for UICollectionViewCell in Interface Builder.

Add PhotosViewController

Rename ViewController.swift to PhotosViewController.swift. Update the class as follows

import UIKit
import SDWebImage

class PhotosViewController: UIViewController, UISearchBarDelegate, PixabayPhotoDownloadDelegate {
    
    @IBOutlet weak var searchBar: UISearchBar!
    @IBOutlet weak var collectionView: UICollectionView!
    
    var service: Services = Services()
    var photos: [Photo] = []
    
    let reuseIdentifier = "PhotoCell"

    override func viewDidLoad() {
        super.viewDidLoad()
        
        collectionView.dataSource = self
        searchBar.delegate = self
        collectionView.delegate = self
        service.delegate = self
        
        searchBar.text = "nature"
        searchForPhotos()
    }

    func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
        searchForPhotos()
        searchBar.resignFirstResponder()
    }
    
    func searchForPhotos() {
        service.makeServiceCall(searchText: searchBar.text!)
    }
    
    func finishedDownloading(photos: [Photo]) {
        DispatchQueue.main.async {
            self.photos = photos
            self.collectionView?.reloadData()
        }
    }
}

extension PhotosViewController: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return photos.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! PhotoCell
        let photo = photos[indexPath.row]

        cell.imageView.frame.size = cell.frame.size
        if let url = URL(string: photo.previewURL) {
            cell.imageView.sd_setImage(with: url, placeholderImage: UIImage(named: "placeholder"))
        }
        
        return cell
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let width = (UIScreen.main.bounds.width - 15) / 4
        return CGSize(width: width, height: width)
    }
    
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let photo = photos[indexPath.row]
        let detailViewController = storyboard?.instantiateViewController(withIdentifier: "DetailViewController") as! DetailViewController
        detailViewController.photo = photo
        present(detailViewController, animated: true, completion: nil)
    }
}

Add DetailViewController

Create a new file named DetailViewController.swift:

import UIKit
import SDWebImage

class DetailViewController: UIViewController {
    
    var photo: Photo?
    var imageView: UIImageView?

    override func viewDidLoad() {
        super.viewDidLoad()

        if let photo = photo {
            imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 320, height: 320))
            if let url = URL(string: photo.largeImageURL) {
                imageView?.sd_setImage(with: url, placeholderImage: UIImage(named: "placeholder"))
                view.addSubview(imageView!)
                
                let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(close))
                view.addGestureRecognizer(tapGestureRecognizer)
            }
        }
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        let size = view.bounds.size
        let imageSize = CGSize(width: size.width, height: size.width)
        imageView?.frame = CGRect(x: 0.0, y: (size.height - imageSize.height)/2.0, width: imageSize.width, height: imageSize.height)
    }
    
    @objc func close() {
        dismiss(animated: true, completion: nil)
    }
}

Download the source code from here.