Convert URLRequest to NSMutableURLRequest

问题

I'm trying to convert a URLRequest to a NSMutableURLRequest in Swift 3.0 but I can't get it to work. This is the code I have:

var request = self.request
URLProtocol.setProperty(true, forKey: "", in: request)

But it says

cannot convert type URLRequest to type NSMutableURLRequest.

When I try to cast using 'as' it just says the cast will always fail. What do I do?

回答1:

The basics of this are get a mutable copy, update the mutable copy then update request with the mutable copy.

let mutableRequest = ((self.request as NSURLRequest).mutableCopy() as? NSMutableURLRequest)!
URLProtocol.setProperty(true, forKey: "", in: mutableRequest)
self.request = mutableRequest as URLRequest

It would be better to use avoid the forced unwrap.

guard let mutableRequest = (self.request as NSURLRequest).mutableCopy() as? NSMutableURLRequest else {
    // Handle the error
    return
}

URLProtocol.setProperty(true, forKey: "", in: mutableRequest)
self.request = mutableRequest as URLRequest

Note: self.request must be declared var not let.

回答2:

Since iOS 10 SDK MutableURLRequest is deprecated in favor of using URLRequest struct type with var keyword. Also URLRequest is bridged to NSMutableURLRequest so you can safely make forced casts:

let  r = URLRequest(url: URL(string: "https://stackoverflow.com")!) as! NSMutableURLRequest
URLProtocol.setProperty("Hello, world!", forKey: "test", in: r)
print(URLProtocol.property(forKey: "test", in: r as! URLRequest)!)

回答3:

Using Swift 4.1, the following solution worked for me

if let mutableRequest = (request as NSURLRequest).mutableCopy() as? NSMutableURLRequest {
    mutableRequest.addValue("VALUE", forHTTPHeaderField: "KEY")
    print(mutableRequest)
}

来源：https://stackoverflow.com/questions/41189959/convert-urlrequest-to-nsmutableurlrequest