使用Swift更改自定义键盘中的字体

Question

早上好。我正在尝试使用Swift编写自定义键盘，键盘的关键点是我想要使用的自定义字体。字体在xcode中工作，问题不在于它的设置。由于我使用Swift很新，我不知道如何做到这一点。这是我的代码：

let buttonTitles1 = ["Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P"]
    let buttonTitles2 = ["A", "S", "D", "F", "G", "H", "J", "K", "L"]
    let buttonTitles3 = ["CP", "Z", "X", "C", "V", "B", "N", "M", "BP"]
    let buttonTitles4 = ["CHG", "SPACE", "RETURN"]

    let row1 = createRowOfButtons(buttonTitles1)
    let row2 = createRowOfButtons(buttonTitles2)
    let row3 = createRowOfButtons(buttonTitles3)
    let row4 = createRowOfButtons(buttonTitles4)

    self.view.addSubview(row1)
    self.view.addSubview(row2)
    self.view.addSubview(row3)
    self.view.addSubview(row4)

    row1.translatesAutoresizingMaskIntoConstraints = false
    row2.translatesAutoresizingMaskIntoConstraints = false
    row3.translatesAutoresizingMaskIntoConstraints = false
    row4.translatesAutoresizingMaskIntoConstraints = false

    addConstraintsToInputView(self.view, rowViews: [row1, row2, row3, row4])


}

func createRowOfButtons(buttonTitles: [NSString]) -> UIView {

    var buttons = [UIButton]()
    var keyboardRowView = UIView(frame: CGRectMake(0, 0, 320, 50))

    for buttonTitle in buttonTitles{

        let button = createButtonWithTitle(buttonTitle as String)

        buttons.append(button)
        keyboardRowView.addSubview(button)
    }

    addIndividualButtonConstraints(buttons, mainView: keyboardRowView)

    return keyboardRowView
}

说实话，我甚至不知道在哪里更改字体。我应该在buttonTitles1部分的createRowOfButtons部分或之后的部分进行此操作吗？ 感谢。