如何在Swift 3中表达一个空URL？

Question

I have an iOS project. I'm working on using Xcode 8 and now Swift 3 . Before I started converting my project from Swift 2 to the latest, I had the following in my AppDelegate :

func application(app: UIApplication, openURL url: NSURL, options: [String : AnyObject]) -> Bool {

    // Transfer incoming file to global variable to be read
    if url != "" {

        // Load from Mail App

        incomingFileTransfer = url

        incomingStatus = "Incoming"

    } else {

        // Regular Load

        print("App Delegate: No incoming file")

        incomingFileTransfer = nil

    }

    return true
}

Worked great and it would see if there was an incoming PDF type file being opened by the app. I have PDF files associated with my app and being to open them within my app.

I used the migration tool to help convert my code to the new Swift 3 code.

It converted my code in the AppDelegate and changed it to:

func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any]) -> Bool {

    // Transfer incoming file to global variable to be read
    if url != "" {

        // Load from Mail App

        incomingFileTransfer = url

        incomingStatus = "Incoming"

    } else {

        // Regular Load

        print("App Delegate: No incoming file")

        incomingFileTransfer = nil

    }

    return true
}

However it gives the error:

Binary operator '!=' cannot be applied to operands of type 'URL' and 'String'

I understand the 'open url' that was an NSURL is now a type URL instead. How do I express an empty URL in Xcode 8 and Swift 3 now? I looked online and cannot find anything about this?

Thank you for the help and advice.

Answer 1

Try to use absoluteString property of URL to compare is it empty.

if url.absoluteString != "" {

}
else {

}

Note: If you just want to check for empty, then batter to use isEmpty property of String in your case it is look like if !url.absoluteString.isEmpty {