ios - 将按钮放在屏幕的左下角

Question

我有这个功能可以创建一个按钮，但即使我添加了一个 subview ，它也没有出现在屏幕上。我也想把它放在屏幕的左下角。我知道如何将它居中，但我无法弄清楚右下角和左下角按钮的位置

// will basically crete the login button
lazy var loginButton: UIButton = {
    let button = UIButton(type: .system)
    button.backgroundColor = UIColor(red: 114, green: 206, blue: 236, alpha: 0)

    button.setTitle("LOG IN", for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setTitleColor(UIColor.white, for: .normal)
    button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 20)

    return button
}()



//will setup constraints for the button
func setupLoginButton(){



}

Answer 1

你必须先给你的按钮一个位置。像这样:

let loginButton: UIButton = UIButton(frame: CGRect(100, 400, 100, 50))

CGRectMake 函数采用以下 4 个参数:

CGRect(CGFloat x, CGFloat y, CGFloat width, CGFloat height);

编辑

 // create button and position it
    let button: UIButton = UIButton(frame: CGRectMake(100, 400, 100, 50))

// set all the other properties you did
    button.backgroundColor = UIColor(red: 114, green: 206, blue: 236, alpha: 0)

    button.setTitle("LOG IN", for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setTitleColor(UIColor.white, for: .normal)
    button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 20)
    // add button to view
    self.view.addSubview(button)

编辑 2

如果你想设置按钮类型，你必须先这样做，因为一旦创建了按钮，你就不能改变它，也不能设置按钮类型:

// create button and set button type
let button = UIButton(type: UIButtonType.System)
// position the button
button.frame = CGRect(x: 30, y: 30, width: 150, height: 150)
// set all the other properties you did
button.backgroundColor = UIColor(red: 114, green: 206, blue: 236, alpha: 0)

button.setTitle("LOG IN", for: .normal)
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitleColor(UIColor.white, for: .normal)
button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 20)
// add button to view
self.view.addSubview(button)