Swift 3：将UIButton扩展添加到ViewController

Question

我是iOS / Swift的初学者，尝试创建一个没有Storyboard的简单应用程序。 我创建了一个UIButton扩展名，我想在我的视图中添加一个简单的按钮（稍后会设置约束）。 不幸的是，按钮不可见。 如果有人帮助我，我将不胜感激。 谢谢！

--- Buttons.swift ---

extension UIButton {

func createRectangleButton(buttonPositionX: Double, buttonPositionY: Double ,buttonWidth: Double, buttonHeight: Double, buttonTilte: String) {
    let button = UIButton(type: .system) as UIButton
    button.frame = CGRect(x: buttonPositionX, y: buttonPositionY, width: buttonWidth, height: buttonHeight)
    button.setTitle(buttonTilte, for: .normal)
    button.backgroundColor = COLOR_WHITE
    button.tintColor = COLOR_BLACK
    }   
}

--- InitialViewController.swift ---

import UIKit 

class InitialViewController: BaseViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    // Gradient Layer
    view.addGradientBackground(colorTop: COLOR_ROYALRED2, colorBottom: COLOR_ROYALRED1)

    // Button
    let startButton = UIButton()
    startButton.createRectangleButton(buttonPositionX: 50, buttonPositionY: 20, buttonWidth: 200, buttonHeight: 50, buttonTilte: "START")
    self.view.addSubview(startButton)

    }
}

Answer 1

请尝试以下操作：

在这里输入代码

extension UIButton {

func createRectangleButton(buttonPositionX: Double, buttonPositionY: Double ,buttonWidth: Double, buttonHeight: Double, buttonTilte: String) {
                let button = self // changes made here
                button.frame = CGRect(x: buttonPositionX, y: buttonPositionY, width: buttonWidth, height: buttonHeight)
                button.setTitle(buttonTilte, for: .normal)
                button.backgroundColor = COLOR_WHITE
                button.tintColor = COLOR_BLACK
            }