IBOutlet and IBAction in Swift

问题

I connected a IBOutlet and IBAction to my button variable from Interface Builder to my View Controller. How do I add an action method to the button in Swift? This code doesn't seem to work.

@IBOutlet var OK: UIButton!
@IBAction func OK(sender: UIButton){}

The Objective-C equivalent I found is:

@interface Controller
{
    IBOutlet id textField; // links to TextField UI object
}

- (IBAction)doAction:(id)sender; // e.g. called when button pushed

回答1:

When you attach a button to the viewController, and create an action (IBAction) using ctrl-drag, you create a method (also called a function) that looks likes this in Swift (if it dose not have arguments):

@IBAction func buttonAction() {}

In objective-C the same thing will look like this:

- (IBAction)buttonAction {}

So that means that @IBAction func OK(sender: UIButton){} is an action method.

If you want to know about the sender argument, I would recommend this SO post.

Edit:

For what you want to do, I create an IBOutlet and an IBAction, that way I can change it's attributes with the outlet variable, and have the action side of things with the IBAction, like what you show above:

@IBOutlet var OK: UIButton!
@IBAction func OK(sender: UIButton){}

For example, if I want to hide the button, I would put this code in the viewDidLoad

OK.hidden = true

The OK in that code is for the outlet variable, if I wanted to print "You pressed me" to the console when the button is pressed, I would use this code:

@IBAction func OK(sender: UIButton){
  println("You pressed me")
}

Above I am using the action to print "You pressed me" to the console.

A few things to note:

When Swift 2.0 gets released println will get changed to print. Also with you action and outlet, I would suggest giving them differing names, to make it easier to differentiate the two, something like this:

@IBOutlet var okOutlet: UIButton!
@IBAction func okAction(sender: UIButton){}

Along with that, you should use camel case when naming variables, constants, functions, etc.

回答2:

One way to do it, is control-drag from your button to your viewcontroller and choose action:

If you have connected your button's action, your code should work just fine.

回答3:

Here are the steps you can follow-

For @IBOutlet

1.Declare Your Interface builder Element property right after class name

class SomeViewController: UIViewController{

    @IBOutlet weak var aTextField : UITextField! ////Your Interface builder Element

2.Hook the IB Element From Storyboard.

For @IBAction

1.Write A method inside your class(say SomeViewController)

@IBAction func anAction(_sender : AnyObject){


}

2.Hook the method from Storyboard.

Hope it might helps.

回答4:

You can simply add action from your storyboard. See the image.

来源：https://stackoverflow.com/questions/32572305/iboutlet-and-ibaction-in-swift

标签

swift

iboutlet