URL Loading System Error Info Keys

Recognize these keys from the user info dictionary of error objects produced by URL Loading APIs.


These keys are only present in the NSURLErrorDomain.



let NSURLErrorFailingURLErrorKey: String

The URL which caused a load to fail.

let NSURLErrorFailingURLPeerTrustErrorKey: String

The state of a failed SSL handshake.

let NSURLErrorFailingURLStringErrorKey: String

The URL which caused a load to fail.

let NSURLErrorBackgroundTaskCancelledReasonKey: String

A key in the error dictionary that provides the reason for canceling a background task.

URL Session Background Task Cancellation Reasons

Reasons that indicate why the system canceled a background task.

let NSURLErrorNetworkUnavailableReasonKey: String

The reason the network was unavailable for a task.

enum URLError.NetworkUnavailableReason

An enumeration of reasons explaining why a task couldn’t satisfy networking constraints.


let NSErrorFailingURLStringKey: String

The URL that caused the error.


See Also


struct URLError

Error codes returned by URL loading APIs.