I have an iOS Xcode 7 Swift 2 project I'm working on.  The app posts photos to Facebook and Twitter using:
var shareToFacebook: SLComposeViewController = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
and
var shareToTwitter: SLComposeViewController = SLComposeViewController(forServiceType: SLServiceTypeTwitter)
Love how easy and simple for just posting a photo to these two social medias. I didn't need or want the APIs for them.
I want to do something similar and simple for Instagram.  What is the best way to do this without having to deal with Instagram API?  Or do I have no choice?
My photo data is saved using NSCoding, not in the DocumentDirectory. I looked here for integration but this is for a photo saved in the app directory.
Just something simple like what I already have for Facebook and Twitter.
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.
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)
                        If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With