在Swift中以编程方式创建UIButton

Question

我正在尝试以编程方式构建UI.如何让这个动作起作用？我正在与Swift一起开发.

viewDidLoad中的代码:

override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let myFirstLabel = UILabel()
        let myFirstButton = UIButton()
        myFirstLabel.text = "I made a label on the screen #toogood4you"
        myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45)
        myFirstLabel.textColor = UIColor.redColor()
        myFirstLabel.textAlignment = .Center
        myFirstLabel.numberOfLines = 5
        myFirstLabel.frame = CGRectMake(15, 54, 300, 500)
        myFirstButton.setTitle("?", forState: .Normal)
        myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
        myFirstButton.frame = CGRectMake(15, -50, 300, 500)
        myFirstButton.addTarget(self, action: "pressed", forControlEvents: .TouchUpInside)
        self.view.addSubview(myFirstLabel)
        self.view.addSubview(myFirstButton)
    }

        func pressed(sender: UIButton!) {
            var alertView = UIAlertView();
            alertView.addButtonWithTitle("Ok");
            alertView.title = "title";
            alertView.message = "message";
            alertView.show();
        }

Answer 1

你只是在选择器名称的末尾错过了冒号.由于按下了一个参数,冒号必须在那里.您的被按下的函数也不应嵌套在viewDidLoad中.

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let myFirstLabel = UILabel()
    let myFirstButton = UIButton()
    myFirstLabel.text = "I made a label on the screen #toogood4you"
    myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45)
    myFirstLabel.textColor = UIColor.redColor()
    myFirstLabel.textAlignment = .Center
    myFirstLabel.numberOfLines = 5
    myFirstLabel.frame = CGRectMake(15, 54, 300, 500)
    myFirstButton.setTitle("?", forState: .Normal)
    myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
    myFirstButton.frame = CGRectMake(15, -50, 300, 500)
    myFirstButton.addTarget(self, action: #selector(myClass.pressed(_:)), forControlEvents: .TouchUpInside)
    self.view.addSubview(myFirstLabel)
    self.view.addSubview(myFirstButton)
}

@objc func pressed(sender: UIButton!) {
    var alertView = UIAlertView()
    alertView.addButtonWithTitle("Ok")
    alertView.title = "title"
    alertView.message = "message"
    alertView.show()
}

编辑:更新以反映Swift 2.2中的最佳实践.应该使用#selector()而不是不推荐使用的文字字符串.

Answer 2

Swift 2.2 Xcode 7.3

由于现在不推荐使用Objective-C String Literals用于按钮回调方法

let button:UIButton = UIButton(frame: CGRectMake(100, 400, 100, 50))
button.backgroundColor = UIColor.blackColor()
button.setTitle("Button", forState: UIControlState.Normal)
button.addTarget(self, action:#selector(self.buttonClicked), forControlEvents: .TouchUpInside)
self.view.addSubview(button)

func buttonClicked() {
     print("Button Clicked")
}

Swift 3 Xcode 8

let button:UIButton = UIButton(frame: CGRect(x: 100, y: 400, width: 100, height: 50))
button.backgroundColor = .black
button.setTitle("Button", for: .normal)
button.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button)

func buttonClicked() {
    print("Button Clicked")
}

Swift 4 Xcode 9

let button:UIButton = UIButton(frame: CGRect(x: 100, y: 400, width: 100, height: 50))
button.backgroundColor = .black
button.setTitle("Button", for: .normal)
button.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button)

@objc func buttonClicked() {
    print("Button Clicked")
}

Answer 3

斯威夫特4

    private func createButton {
        let sayButtonT = UIButton(type: .custom)
        sayButtonT.addTarget(self, action: #selector(sayAction(_:)), for: .touchUpInside)
    }

    @objc private func sayAction(_ sender: UIButton?) {

    }

Answer 4

斯威夫特3

let button = UIButton(frame: CGRect(x: 20, y: 20, width: 200, height: 60))
 button.setTitle("Email", for: .normal)
 button.backgroundColor = .white
 button.setTitleColor(UIColor.black, for: .normal)
 button.addTarget(self, action: #selector(self.buttonTapped), for: .touchUpInside)
 myView.addSubview(button)



@objc func buttonTapped(sender : UIButton) {
                //Write button action here
            }

Answer 5

是的在模拟器中.有时它不会识别选择器,看起来有一个错误.即使我不面对你的代码,我只是改变了动作名称(选择器).有用

let buttonPuzzle:UIButton = UIButton(frame: CGRectMake(100, 400, 100, 50))
buttonPuzzle.backgroundColor = UIColor.greenColor()
buttonPuzzle.setTitle("Puzzle", forState: UIControlState.Normal)
buttonPuzzle.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
buttonPuzzle.tag = 22;
self.view.addSubview(buttonPuzzle)

这里有一个示例选择器函数:

func buttonAction(sender:UIButton!) {
    var btnsendtag:UIButton = sender
    if btnsendtag.tag == 22 {            
        //println("Button tapped tag 22")
    }
}

Answer 6

您应该能够通过访问UIButton的titleLabel属性以编程方式创建自定义UI按钮.

Swift中的每类引用:关于titleLabel属性,它表示"尽管此属性是只读的,但它自己的属性是可读/写的.主要使用这些属性来配置按钮的文本."

在Swift中,您可以直接修改titleLabel的属性,如:

let myFirstButton = UIButton()
myFirstButton.titleLabel!.text = "I made a label on the screen #toogood4you"
myFirstButton.titleLabel!.font = UIFont(name: "MarkerFelt-Thin", size: 45)
myFirstButton.titleLabel!.textColor = UIColor.red
myFirstButton.titleLabel!.textAlignment = .center
myFirstButton.titleLabel!.numberOfLines = 5
myFirstButton.titleLabel!.frame = CGRect(x: 15, y: 54, width: 300, height: 500)

编辑

Swift 3.1语法

Answer 7

尝试这些..我希望它有帮助......

override func viewDidLoad() {
super.viewDidLoad()  

    let btn = UIButton()
    btn.frame = CGRectMake(10, 10, 50, 50)  //set frame
    btn.setTitle("btn", forState: .Normal)  //set button title
    btn.setTitleColor(UIColor.redColor(), forState: .Normal) //set button title color
    btn.backgroundColor = UIColor.greenColor() //set button background color
    btn.tag = 1 // set button tag
    btn.addTarget(self, action: "btnclicked:", forControlEvents: .TouchUpInside) //add button action
    self.view.addSubview(btn) //add button in view

}

这些是按钮点击事件..

func btnclicked(sender: UIButton!) 
{
    //write the task you want to perform on buttons click event..
}

Answer 8

Swift 3：您可以以UIButton编程方式创建

要么在方法范围内，例如在ViewDidLoad() 一定要向按钮添加约束，否则你不会看到它

let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.target(forAction: #selector(buttonAction), withSender: self)
//button.backgroundColor etc

view.addSubview(button)

@objc func buttonAction() {
   //some Action
}

或在您的范围之外作为全局变量从您的任何地方访问它 module

let button: UIButton = {
   let b = UIButton()
   b.translatesAutoresizingMaskIntoConstraints = false
   //b.backgroundColor etc
   return b
}()

然后你设置约束

func setupButtonView() {
   view.addSubview(button)
   button.widthAnchor.constraint(equalToConstant: 40).isActive = true
   button.heightAnchor.constraint(equalToConstant: 40).isActive = true
   // etc

}

Answer 9

斯威夫特 5.0

        let button = self.makeButton(title: "Login", titleColor: .blue, font: UIFont.init(name: "Arial", size: 18.0), background: .white, cornerRadius: 3.0, borderWidth: 2, borderColor: .black)
        view.addSubview(button)
        // Adding Constraints
        button.heightAnchor.constraint(equalToConstant: 40).isActive = true
        button.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 40).isActive = true
        button.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -40).isActive = true
        button.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -400).isActive = true
        button.addTarget(self, action: #selector(pressed(_ :)), for: .touchUpInside)

       // Define commmon method
        func makeButton(title: String? = nil,
                           titleColor: UIColor = .black,
                           font: UIFont? = nil,
                           background: UIColor = .clear,
                           cornerRadius: CGFloat = 0,
                           borderWidth: CGFloat = 0,
                           borderColor: UIColor = .clear) -> UIButton {
        let button = UIButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        button.setTitle(title, for: .normal)
        button.backgroundColor = background
        button.setTitleColor(titleColor, for: .normal)
        button.titleLabel?.font = font
        button.layer.cornerRadius = 6.0
        button.layer.borderWidth = 2
        button.layer.borderColor = UIColor.red.cgColor
        return button
      }
        // Button Action
         @objc func pressed(_ sender: UIButton) {
                print("Pressed")
          }