Can I get the element by Tag from iOS?

Use the viewWithTag method. e.g. if your button is in your controller's view and your button's tag is 100 the following line will return the button:

UIButton *button = (UIButton *)[self.view viewWithTag:100];

EDIT:

Get view with particular tag in Swift -

let view = self.view.viewWithTag(100)

If you want to make sure you have the specific type of view, say a UIButton, you should check the type:

if let button = self.view.viewWithTag(100) as? UIButton {
    //Your code
}

UIButton *button=(UIButton *)[self.view viewWithTag:tag]; 

//Now you can get your button based on tag value