Swift port of http://qiita.com/uro_uro_/items/ef700c85eb0aaff1a623

.swift

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    for subview in view.subviews {
        if subview.isKindOfClass(UITextField) {
            subview.resignFirstResponder()
        }
    }
}