Issue while adding action to UIButton in Swift 3.0

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You don’t need to add () to the end of a method when you are passing that method as a selector! This is because () is used to specify the arguments when you are calling the method. But you don’t want to call the method, do you? So remove the ()!

 //Adding BUtton
let btn = UIButton()

btn.frame = CGRect(x: 100, y: 100, width: 200, height: 100)

// () removed!
btn.addTarget(self, action: #selector(self.printname), for: UIControlEvents.touchUpInside)

self.view.addSubview(btn)

//Method to be called
func printname()
{
    print("button pressed")
}

This is the same as passing a closure to a method:

doStuff(withClosure: myMethod)

func myMethod() {
    // ...
}

This holds true no matter how many arguments there are in the method passed in.

EDIT: I just saw that your printname method seems to be inside another method. If this is true, please move it to the class level! Also, you need to add a sender argument to printname:

func printname(sender: UIButton) {
    // ...
}

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