Post UIImage to Instagram using Swift similar to SLComposeViewController

Updated for Swift 3

import UIKit
import Foundation

class InstagramManager: NSObject, UIDocumentInteractionControllerDelegate {

    private let kInstagramURL = "instagram://app"
    private let kUTI = "com.instagram.exclusivegram"
    private let kfileNameExtension = "instagram.igo"
    private let kAlertViewTitle = "Error"
    private let kAlertViewMessage = "Please install the Instagram application"

    var documentInteractionController = UIDocumentInteractionController()

    // singleton manager
    class var sharedManager: InstagramManager {
        struct Singleton {
            static let instance = InstagramManager()
        }
        return Singleton.instance
    }

    func postImageToInstagramWithCaption(imageInstagram: UIImage, instagramCaption: String, view: UIView) {
        // called to post image with caption to the instagram application

        let instagramURL = NSURL(string: kInstagramURL)

        if UIApplication.shared.canOpenURL(instagramURL! as URL) {

            let jpgPath = (NSTemporaryDirectory() as NSString).appendingPathComponent(kfileNameExtension)

            do {
                try UIImageJPEGRepresentation(imageInstagram, 1.0)?.write(to: URL(fileURLWithPath: jpgPath), options: .atomic)

            } catch {

                print(error)
            }

            let rect = CGRect(x: 0, y: 0, width: 612, height: 612)
            let fileURL = NSURL.fileURL(withPath: jpgPath)
            documentInteractionController.url = fileURL
            documentInteractionController.delegate = self
            documentInteractionController.uti = kUTI

            // adding caption for the image
            documentInteractionController.annotation = ["InstagramCaption": instagramCaption]
            documentInteractionController.presentOpenInMenu(from: rect, in: view, animated: true)
        } else {

            /// display some message about how it didn't work
            /// Like: UIAlertController(title: kAlertViewTitle, message: kAlertViewMessage, preferredStyle: .alert)
        }
    }
}

and then in the ViewController you want to call it in...

InstagramManager.sharedManager.postImageToInstagramWithCaption(imageInstagram: <YOUR IMAGE>, instagramCaption: shareText, view: self.view)

This opens the 'open-in' function if Instagram is installed

I looked here and found a solution:

I created an NSObject:

import UIKit
import Foundation

class InstagramManager: NSObject, UIDocumentInteractionControllerDelegate {

    private let kInstagramURL = "instagram://app"
    private let kUTI = "com.instagram.exclusivegram"
    private let kfileNameExtension = "instagram.igo"
    private let kAlertViewTitle = "Error"
    private let kAlertViewMessage = "Please install the Instagram application"

    var documentInteractionController = UIDocumentInteractionController()

    // singleton manager
    class var sharedManager: InstagramManager {
        struct Singleton {
            static let instance = InstagramManager()
        }
        return Singleton.instance
    }

    func postImageToInstagramWithCaption(imageInstagram: UIImage, instagramCaption: String, view: UIView) {
        // called to post image with caption to the instagram application

        let instagramURL = NSURL(string: kInstagramURL)
        if UIApplication.sharedApplication().canOpenURL(instagramURL!) {
            let jpgPath = (NSTemporaryDirectory() as NSString).stringByAppendingPathComponent(kfileNameExtension)
            UIImageJPEGRepresentation(imageInstagram, 1.0)!.writeToFile(jpgPath, atomically: true)
            let rect = CGRectMake(0,0,612,612)
            let fileURL = NSURL.fileURLWithPath(jpgPath)
            documentInteractionController.URL = fileURL
            documentInteractionController.delegate = self
            documentInteractionController.UTI = kUTI

            // adding caption for the image
            documentInteractionController.annotation = ["InstagramCaption": instagramCaption]
            documentInteractionController.presentOpenInMenuFromRect(rect, inView: view, animated: true)
        } else {

            // alert displayed when the instagram application is not available in the device
            UIAlertView(title: kAlertViewTitle, message: kAlertViewMessage, delegate:nil, cancelButtonTitle:"Ok").show()
        }
    }

}

Then in my @IBAction I used:

let image = self.photoImageView.image
InstagramManager.sharedManager.postImageToInstagramWithCaption(image!, instagramCaption: "\(self.description)", view: self.view)

This opens bring a menu up with the 'open-in' style and the user can open the app in Instagram (if installed).

Here is a reusable class with swift 4+. Working in Xcode 10.1.

1. Make swift empty file.

2. copy and paste the below code into the file.

   import UIKit
   import Foundation
   
   class InstagramHelper: NSObject, UIDocumentInteractionControllerDelegate {
   
       private let kInstagramURL = "instagram://den3079"
       private let kUTI = "com.instagram.exclusivegram"
       private let kfileNameExtension = "instagram.igo"
       private let kAlertViewTitle = "Error"
       private let kAlertViewMessage = "Please install the Instagram application"
   
       var documentInteractionController = UIDocumentInteractionController()
   
       // singleton manager
       class var sharedManager: InstagramHelper {
           struct Singleton {
               static let instance = InstagramHelper()
           }
           return Singleton.instance
       }
   
   
       func postImageToInstagramWithCaption(imageInstagram: UIImage, instagramCaption: String, controller: UIViewController) {
           // called to post image with caption to the instagram application
   
           let instagramURL = URL(string: kInstagramURL)
   
           DispatchQueue.main.async {
   
               if UIApplication.shared.canOpenURL(instagramURL!) {
   
                   let jpgPath = (NSTemporaryDirectory() as NSString).appendingPathComponent(self.kfileNameExtension)
                   if let jpegData = UIImageJPEGRepresentation(imageInstagram, 1.0) {
                       do {
                           try jpegData.write(to: URL(fileURLWithPath: jpgPath), options: .atomicWrite)
   
                       } catch {
                           print("write image failed")
                       }
                   }else {
                       let jpegData = UIImagePNGRepresentation(imageInstagram)
                       do {
                           try jpegData?.write(to: URL(fileURLWithPath: jpgPath), options: .atomicWrite)
   
                       } catch {
                           print("write image failed")
                       }
                   }
                   let fileURL = NSURL.fileURL(withPath: jpgPath)
                   self.documentInteractionController.url = fileURL
                   self.documentInteractionController.delegate = self
                   self.documentInteractionController.uti = self.kUTI
   
                   // adding caption for the image
                   self.documentInteractionController.annotation = ["InstagramCaption": instagramCaption]
                   self.documentInteractionController.presentOpenInMenu(from: controller.view.frame, in: controller.view, animated: true)
   
               } else {
   
                   // alert displayed when the instagram application is not available in the device
                   self.showAlert("", message: self.kAlertViewMessage, controller: controller)
               }
           }
       }
    func showAlert(_ title: String, message: String, controller : UIViewController){
   
       let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
       let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: { action -> Void in
           //Just dismiss the action sheet
           let selector: Selector = NSSelectorFromString("alertOkButtonHandler")
           if controller.responds(to: selector){
               _ = controller.perform(selector)
           }
       })
       alert.addAction(okAction)
       controller.present(alert, animated: true, completion: nil)
   }}
   

And use of this function in ViewController class.

InstagramHelper.sharedManager.postImageToInstagramWithCaption(imageInstagram: img!, instagramCaption: "www.google.com", controller: self)