Explicitly specified type 'NSURL?' issue while updating to Swift 3 - swift

Question

I am having issues while updating my iOS app's code to the latest version of Swift.
I have a function:
public class func gifWithURL(gifUrl:String) -> UIImage? {
// Validate URL
guard let bundleURL:NSURL? = NSURL(string: gifUrl)
else {
print("SwiftGif: This image named \"\(gifUrl)\" does not exist")
return nil
}
// Validate data
guard let imageData = NSData(contentsOf: bundleURL! as URL) else {
print("SwiftGif: Cannot turn image named \"\(gifUrl)\" into NSData")
return nil
}
return gifWithData(data: imageData)
}
And am getting a warning on the following line:
guard let bundleURL:NSURL? = NSURL(string: gifUrl)
and am getting the warning:
Explicitly specified type 'NSURL?' adds an additional level of optional to the initializer, making the optional check always succeed
Xcode allows me to fix the problem automatically. When I do this auto-fix, my code changes to:
guard let bundleURL:NSURL NSURL(string: gifUrl)
Which is obviously not the correct syntax.
I am unsure what I need to add/remove to get my code fully up to date with Swift 3 standards and working.

Answer 1

NSURL(string:) will return optional NSURL? instance and you are already optionally wrapping it with guard so remove the : NSURL? because you are setting it again optional instead of non-optional also, in Swift 3 use native URL and Data instead of NSURL and NSData. The whole code would be like.
guard let bundleURL = URL(string: gifUrl), let imageData = try? Data(contentsOf: bundleURL) else {
print("SwiftGif: This image named \"\(gifUrl)\" does not exist")
return nil
}
//Access the imageData here
Note: Data(contentsOf:) will throws exception so you need to catch it using do try catch block.

Answer 2

You are doing it too complicated. In Swift 3, we don't use NSURL. It's just URL:
guard let bundleURL = URL(string: gifUrl) else {
print("SwiftGif: This image named \"\(gifUrl)\" does not exist")
return nil
}
Then you can also get rid of your dangerous force-cast:
guard let imageData = NSData(contentsOf: bundleURL) else {
print("SwiftGif: Cannot turn image named \"\(gifUrl)\" into NSData")
return nil
}