Returns whether the resource pointed to by a file URL can be reached.
- iOS 4.0+
- macOS 10.6+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
The URL to check.
The error that occurred when the resource could not be reached.
true if the resource is reachable; otherwise,
This function synchronously checks if the file at the provided URL is reachable. Checking reachability is appropriate when making decisions that do not require other immediate operations on the resource, such as periodic maintenance of user interface state that depends on the existence of a specific document. For example, you might remove an item from a download list if the user deletes the file.
If your app must perform operations on the file, such as opening it or copying resource properties, it is more efficient to attempt the operation and handle any failure that may occur.
If this function returns
false, the object pointer referenced by
error is populated with additional information.