CODEWITHSUNDEEP
iosswift
Lee Whitney III
Lee Whitney III

Reputation: 10978

How do you check if NSURLRequest.URL is nil?

How should this be done in Swift? The compiler error is "Cannot invoke '==' with an argument list of type '(NSURL, NilLiteralConvertible)'"

    var request = NSURLRequest()
    if request.URL == nil {
    }

It seems like the normal pattern is to declare types optional when an object may not have a value.

However in this case I'm not sure why Apple did not declare the URL property as an optional var within the NSURLRequest class.

Upvotes: 0

Views: 2637

Answers (3)

jaime
jaime

Reputation: 926

Good question. Fortunately, request.URL.absoluteString is an optional. I think this will do what you need:

if (request.URL.absoluteString == nil) { ... }

Or, since NSMutableURLRequest uses an optional when URL is fetched, another option is to use NSMutableURLRequest() instead, if that works for your use case.

var request = NSMutableURLRequest()
if (request.URL == nil) { ... }

Upvotes: 1

Matthias Bauch
Matthias Bauch

Reputation: 90127

You don't. URL is a non-optional, read only variable of NSURLRequest.

If you stay in swift there is no way that this parameter can be nil. Unless you use the NSURLRequest() initializer, which is pretty pointless because URL is read-only and you can't set it.

Use one of the designated initializers. Or use NSMutableURLRequest, which has a URL variable that is not read-only and an optional.

Upvotes: 1

Rob Napier
Rob Napier

Reputation: 299623

Because this would be a pain in the normal (and only meaningful) use case. The normal use case is to call the designated initializer (initWithURL:), or something that calls the designated initializer with a real URL. So in all normal code, you'd have to unload the NSURL? every single time. That would get old fast for nothing.

If this were a from-scratch Swift object, then it would have no public init(), but you can't remove that because it's legal (though meaningless) ObjC. (Well, maybe they can remove it; that may be worth a radar to mark its init() private.)

So this is a compromise with ObjC-as-typically-programmed vs ObjC-as-legal-syntax. Many of the weirdnesses around calling Cocoa from Swift boil down to this.

If ObjC dev used [[NSURLRequest alloc] init] as a common pattern, then URL certainly would have been an optional. ObjC devs pretty much never do this, so it isn't.

As a note, if you're finding yourself in a case where NSURLRequest() seems useful, the really right answer is almost certainly to use an NSURLRequest? instead.

Upvotes: 3

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