How do I create a basic UIButton programmatically?

- (void)viewDidLoad {
    [super viewDidLoad];
    [self addMyButton];   // Call add button method on view load
}

- (void)addMyButton{    // Method for creating button, with background image and other properties

    UIButton *playButton = [[UIButton buttonWithType:UIButtonTypeRoundedRect] retain];
    playButton.frame = CGRectMake(110.0, 360.0, 100.0, 30.0);
    [playButton setTitle:@"Play" forState:UIControlStateNormal];
    playButton.backgroundColor = [UIColor clearColor];
    [playButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal ];
    UIImage *buttonImageNormal = [UIImage imageNamed:@"blueButton.png"];
    UIImage *strechableButtonImageNormal = [buttonImageNormal stretchableImageWithLeftCapWidth:12 topCapHeight:0];
    [playButton setBackgroundImage:strechableButtonImageNormal forState:UIControlStateNormal];
    UIImage *buttonImagePressed = [UIImage imageNamed:@"whiteButton.png"];
    UIImage *strechableButtonImagePressed = [buttonImagePressed stretchableImageWithLeftCapWidth:12 topCapHeight:0];
    [playButton setBackgroundImage:strechableButtonImagePressed forState:UIControlStateHighlighted];
    [playButton addTarget:self action:@selector(playAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:playButton];  
}

Here you can create dynamically a UIButton:

//For button image
UIImage *closebtnimg = [UIImage imageNamed:@"close_btn.png"];
//Custom type button
btnclose = [[UIButton buttonWithType:UIButtonTypeCustom]retain];
//Set frame of button means position
btnclose.frame = CGRectMake(103, 257, 94, 32);
//Button with 0 border so it's shape like image shape
[btnclose.layer setBorderWidth:0];
//Set title of button
[btnclose setTitle:@"CLOSE" forState:UIControlStateNormal];
[btnclose addTarget:self action:@selector(methodname:) forControlEvents:UIControlEventTouchUpInside];
//Font size of title
btnclose.titleLabel.font = [UIFont boldSystemFontOfSize:14];
//Set image of button
[btnclose setBackgroundImage:closebtnimg forState:UIControlStateNormal];

In Swift 5 and Xcode 10.2

Basically we have two types of buttons.

1) System type button

2) Custom type button (In custom type button we can set background image for button)

And these two types of buttons has few control states https://developer.apple.com/documentation/uikit/uicontrol/state

Important states are

1) Normal state

2) Selected state

3) Highlighted state

4) Disabled state etc...

//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
    }
}

UIButton *btnname = [UIButton buttonWithType:UIButtonTypeRoundedRect];

[btnname setTitle:@"Click Me" forState:UIControlStateNormal];

btnname.frame = CGRectMake(10, 10, 100, 140);

[self.view addSubview:btnname];

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];