对于Swift 2.0:

let btnObject : UIButton  = UIButton() 
btnObject.frame = CGRect(x: 8, y: 89, width: 70, height: 22)

btnObject.titleLabel?.font = UIFont(name: "Helvetica Neue", size: 13)
btnObject.titleLabel?.textColor = UIColor.whiteColor()
btnObject.backgroundColor = UIColor(red: 189/255, green: 176/255, blue: 0/255, alpha: 1)
btnObject.titleLabel?.textAlignment = NSTextAlignment.Center
btnObject.addTarget(self, action: "btnbtnObjectClick:", forControlEvents: UIControlEvents.TouchUpInside)
subView.addSubview(btnObject)

这是一个创建三个按钮的例子。只是移动他们的位置。

UIImage *buttonOff = [UIImage imageNamed:@"crysBallNorm.png"];
UIImage *buttonOn = [UIImage imageNamed:@"crysBallHigh.png"];

UIButton *predictButton = [UIButton alloc];
predictButton = [UIButton buttonWithType:UIButtonTypeCustom];
predictButton.frame = CGRectMake(180.0, 510.0, 120.0, 30.0);
[predictButton setBackgroundImage:buttonOff forState:UIControlStateNormal];
[predictButton setBackgroundImage:buttonOn forState:UIControlStateHighlighted];
[predictButton setTitle:@"Predict" forState:UIControlStateNormal];
[predictButton setTitleColor:[UIColor purpleColor] forState:UIControlStateNormal];
[predictButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:predictButton];

对于Swift 2.0:

let btnObject : UIButton  = UIButton() 
btnObject.frame = CGRect(x: 8, y: 89, width: 70, height: 22)

btnObject.titleLabel?.font = UIFont(name: "Helvetica Neue", size: 13)
btnObject.titleLabel?.textColor = UIColor.whiteColor()
btnObject.backgroundColor = UIColor(red: 189/255, green: 176/255, blue: 0/255, alpha: 1)
btnObject.titleLabel?.textAlignment = NSTextAlignment.Center
btnObject.addTarget(self, action: "btnbtnObjectClick:", forControlEvents: UIControlEvents.TouchUpInside)
subView.addSubview(btnObject)

UIButton * tmpBtn = [UIButton buttonWithType:UIButtonTypeCustom];
[tmpBtn addTarget:self action:@selector(clearCart:) forControlEvents:UIControlEventTouchUpInside];
tmpBtn.tag = k;
tmpBtn.frame = CGRectMake(45, 0, 15, 15);
[tmpBtn setBackgroundImage:[UIImage imageNamed:@"CloseButton.png"] forState:UIControlStateNormal];
[self.view addSubview:tmpBtn];

Swift 3版本应该是:

let myButton:UIButton = {
    let myButton = UIButton() // If you want to set the type use like
                              // UIButton(type: .RoundedRect) or
                              // UIButton(type: .Custom)
    myButton.setTitle("Hai Touch Me", for: .normal)
    myButton.setTitleColor(UIColor.blue, for: .normal)
    myButton.frame = CGRect(x: 20, y: 20, width: 100, height: 40)

    myButton.addTarget(self, action: #selector(ViewController.pressedAction(_:)), for: .touchUpInside)
    self.view.addSubview(myButton)

    return myButton
}()

在Swift 5和Xcode 10.2中

基本上我们有两种类型的按钮。

1)系统类型按钮

2)自定义类型按钮(在自定义类型按钮中，我们可以为按钮设置背景图像)

而且这两种类型的按钮控制状态很少https://developer.apple.com/documentation/uikit/uicontrol/state

重要的州有

1)正常状态

2)选定状态

3)高亮状态

4)禁用状态……

//For system type button
let button = UIButton(type: .system)
button.frame = CGRect(x: 100, y: 250, width: 100, height: 50)
//  button.backgroundColor = .blue
button.setTitle("Button", for: .normal)
button.setTitleColor(.white, for: .normal)
button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 13.0)
button.titleLabel?.textAlignment = .center//Text alighment center
button.titleLabel?.numberOfLines = 0//To display multiple lines in UIButton
button.titleLabel?.lineBreakMode = .byWordWrapping//By word wrapping
button.tag = 1//To assign tag value
button.btnProperties()//Call UIButton properties from extension function
button.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button)

//For custom type button (add image to your button)
let button2 = UIButton(type: .custom)
button2.frame = CGRect(x: 100, y: 400, width: 100, height: 50)
//        button2.backgroundColor = .blue
button2.setImage(UIImage.init(named: "img.png"), for: .normal)
button2.tag = 2
button2.btnProperties()//Call UIButton properties from extension function
button2.addTarget(self, action:#selector(self.buttonClicked), for: .touchUpInside)
self.view.addSubview(button2)

@objc func buttonClicked(sender:UIButton) {
    print("Button \(sender.tag) clicked")
}

//You can add UIButton properties using extension
extension UIButton {
    func btnProperties() {
        layer.cornerRadius = 10//Set button corner radious
        clipsToBounds = true
        backgroundColor = .blue//Set background colour
        //titleLabel?.textAlignment = .center//add properties like this
    }
}