对于Swift 2.2(带有新的“selector”声明)。

let btn = UIButton(type: UIButtonType.System) as UIButton
btn.frame = CGRectMake(0, 0, 100, 20) // set any frame you want
btn.setTitle("MyAction", forState: UIControlState.Normal)
btn.addTarget(self, action: #selector(MyClass.myAction(_:)), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(btn)


func myAction(sender:UIButton!){
  // Some action 
}

UIButton *button=[UIButton buttonWithType:UIButtonTypeCustom];

[button setTitle:@"Click" forState:UIControlStateNormal];

[button setTitleColor:[UIColor blackColor]forState:UIControlStateNormal];

button.frame=CGRectMake(self.view.frame.origin.x+10,self.view.frame.size.height/2, self.view.frame.size.width-20, self.view.frame.size.height-500);

 button.titleLabel.font=[UIFont fontWithName:@"Helvetica" size:20];

[button addTarget:selfaction:@selector(aMethod)forControlEvents:UIControlEventTouchUpInside];

[button setBackgroundColor:[UIColor grayColor]];

[self.view addSubview:button];

UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self 
           action:@selector(aMethod:)
 forControlEvents:UIControlEventTouchUpInside];
[button setTitle:@"Show View" forState:UIControlStateNormal];
button.frame = CGRectMake(10.0, 100.0, 300.0, 20.0);
[self.view addSubview:button];

从Swift 3开始，语法有了一些变化。

以下是如何创建Swift 3的基本按钮:

    let button = UIButton(type: UIButtonType.system) as UIButton
    button.frame = CGRect(x: 100, y: 100, width: 100, height: 50)
    button.backgroundColor = UIColor.green
    button.setTitle("Example Button", for: UIControlState.normal)
    self.view.addSubview(button)

以下是Swift自以前版本以来所做的更改:

let button = UIButton(type: UIButtonType.System) as UIButton

// system no longer capitalised

button.frame = CGRectMake(100, 100, 100, 50)

// CGRectMake has been removed as of Swift 3

button.backgroundColor = UIColor.greenColor()

// greenColor replaced with green

button.setTitle("Example Button", forState: UIControlState.Normal)

// normal is no longer capitalised

self.view.addSubview(button)

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 *addProject = [UIButton buttonWithType: UIButtonTypeRoundedRect];
addProject.frame = CGRectMake(210, 285, 100, 18);
[addProject setTitle:@"Show View" forState:UIControlStateNormal];
[addProject addTarget:self action:@selector(addProjectPressed:) forControlEvents:UIControlEventTouchUpInside];
[_scrollView addSubview:addProject];