Override non-dynamic class delaration [duplicate]

Question

With new Xcode 8.3, I get the error:

Cannot override a non-dynamic class declaration from an extension

from the line of code:

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell

How I can avoid this warning?

Answer 1

Extensions can add new functionality to a type, but they cannot override existing functionality.

You have two options:

1. Move your method inside the Class-scope, instead of extension.

2. Add dynamic type to your method (where it's defined), like example.

Example:

@objc open dynamic func onLog(_ message: String) -> Void {
    print("Info: \(message)");
}

Answer 2

which means, you can't not override like super class delegate method in extension. the way you can do is mv extension override method to subclass declare.

final class DEMO, UITableViewDataSource, UITableViewDelegate { 

    override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
         return sectionHeader
    }

    override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
         return 40
    }

}