Class conforming to protocol as function parameter in Swift

Question

In Objective-C, it\'s possible to specify a class conforming to a protocol as a method parameter. For example, I could have a method that only allows a UIViewControlle

Answer 1

You can define foo as a generic function and use type constraints to require both a class and a protocol.

Swift 4

func foo(vc: T) {
    .....
}

Swift 3 (works for Swift 4 also)

func foo(vc:T) where T:UITableViewDataSource { 
    ....
}

Swift 2

func foo(vc: T) {
    // access UIViewController property
    let view = vc.view
    // call UITableViewDataSource method
    let sections = vc.numberOfSectionsInTableView?(tableView)
}