Why is my Plaid Link Integration not opening the Link UI - swift

Question

I am attempting to integrate with Plaid, their documentation is a link confusing to follow and their support team informed me they are working on it. I also reached out to them to see if they could help me with my current integration but they informed me they are not able to look at my code because every integration is different.
Per the Plaid documentation I added my ngrok url to the redirect uri section in the dashboard (This works with the Plaid Link demo app: https://github.com/plaid/plaid-link-ios).
Also I added allow arbitrary load to the info plist.
I was able to get their Plaid Link-demo app up and running but when I try to place this code in my project I get the following error:
Thread 12: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
// MARK: Start Plaid Link using a Link token
// For details please see https://plaid.com/docs/#create-link-token
func presentPlaidLinkUsingLinkToken() {
#warning("Replace <#GENERATED_LINK_TOKEN#> below with your link_token")
// In your production application replace the hardcoded linkToken below with code that fetches an link_token
// from your backend server which in turn retrieves it securely from Plaid, for details please refer to
// https://plaid.com/docs/#create-link-token
let linkToken = "TOKEN HERE"
// <!-- SMARTDOWN_PRESENT_LINKTOKEN -->
// With custom configuration using a link_token
var linkConfiguration = LinkTokenConfiguration(token: linkToken) { success in
print("public-token: \(success.publicToken) metadata: \(success.metadata)")
}
linkConfiguration.onExit = { exit in
if let error = exit.error {
print("exit with \(error)\n\(exit.metadata)")
} else {
print("exit with \(exit.metadata)")
}
}
let result = Plaid.create(linkConfiguration)
switch result {
case .failure(let error):
print("Unable to create Plaid handler due to: \(error)")
case .success(let handler):
// UI Update code here
handler.open(presentUsing: .viewController(self))
self.linkHandler = handler
}
// <!-- SMARTDOWN_PRESENT_LINKTOKEN -->
}
#IBAction func refreshButtonAction(_ sender: Any) {
// UI Update code here
self.presentPlaidLinkUsingLinkToken()
}
I tried to place the self.presentPlaidLinkUsingLinkToken() into the following snippet:
DispatchQueue.main.async {
self.presentPlaidLinkUsingLinkToken()
}
Also per the Plaid documentation I added the following method within my App delegate swift file:
// MARK: Continue Plaid Link for iOS to complete an OAuth authentication flow
// <!-- SMARTDOWN_OAUTH_SUPPORT -->
func application(_ application: UIApplication,
continue userActivity: NSUserActivity,
restorationHandler: #escaping ([UIUserActivityRestoring]?) -> Void
) -> Bool {
guard userActivity.activityType == NSUserActivityTypeBrowsingWeb, let webpageURL = userActivity.webpageURL else {
return false
}
// Check that the userActivity.webpageURL is the oauthRedirectUri
// configured in the Plaid dashboard.
guard let linkOAuthHandler = window?.rootViewController as? LinkOAuthHandling,
let handler = linkOAuthHandler.linkHandler,
webpageURL.host == linkOAuthHandler.oauthRedirectUri?.host &&
webpageURL.path == linkOAuthHandler.oauthRedirectUri?.path
else {
return false
}
// Continue the Link flow
if let error = handler.continueFrom(redirectUri: webpageURL) {
print("Unable to continue from redirect due to: \(error)")
}
return true
}
// <!-- SMARTDOWN_OAUTH_SUPPORT -->
But the same error occurs. Any suggestions will be appreciated.

Answer 1

In case anyone is having issues with this, I was able to figure it out. It is something incorrect in their cocoapod. Once, I downloaded and dragged the LinkKit Framework everything worked as expected. Also Plaid does not use their own cocoapod in their demo project, they do the manual install. Maybe they are working on this issue.

Answer 2

It's hard to tell without seeing the code in your application calling presentPlaidUsingLinkToken(), but your application is crashing on Thread 12. UIKit is not multi-threaded, so if you are presenting a view controller on a background thread you can expect crashes.
I see you tried a DispatchQueue.main.async, however I suspect you may have another threading issue going on.

Answer 3

Just putting this out there since this is one of few results for this issue: My issue was that I wasn't retaining the Handler object. As a result, the Plaid UI would never appear and no events would fire, leaving me with an endless spinner. Simply maintaining the reference in the class did the trick (as shown in the sample project and mentioned in passing in the documentation).

Answer 4

Kona Farry's solution above works. From Plaid docs:
Create a Handler - A Handler is a one-time use object used to open a Link session. The Handler must be retained for the duration of the Plaid SDK flow.