ボタンをタップした時に○○する、を Java と Swift と Xamarin で比較する

//MainActivity.java
button1.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        label1.setText("pushed!!");        
    }
});

//MainActivity.cs
buttonOk.Click += (_, e)
    => label1.Text = "pushed!!";

//ViewController.swift
buttonOK.addTarget(self, action: 
    #selector(ViewController.onTouch(_:)), 
    forControlEvents: .TouchUpInside)
・・・
func onTouch(sender: AnyObject) {
    label1.text = "pushed!!"
}

//ViewColtroller.cs
buttonOk.TouchUpInside += (_, e) 
    => label1.Text = "pushed!!";