IBOutlet and IBAction

Question

What is the purpose of using IBOutlets and IBActions in Xcode and Interface Builder   Does it make any difference if I don t use IBOutlets and IBActions     Swift    IBOutlet weak var textField  UITextField    IBAction func buttonPressed   sender  Any                  Objective-C    property  nonatomic  weak  IBOutlet UITextField  textField   -  IBAction buttonPressed  id sender

User · Answer

Interface Builder uses them to determine what members and messages can be 'wired' up to the interface controls you are using in your window/view.

IBOutlet and IBAction are purely there as markers that Interface Builder looks for when it parses your code at design time, they don't have any affect on the code generated by the compiler.

User · Answer

Ran into the diagram while looking at key-value coding  thought it might help someone  It helps with understanding of what IBOutlet is   By looking at the flow  one could see that IBOutlets are only there to match the property name with a control name in the Nib file

User · Answer

You need to use IBOutlet and IBAction if you are using interface builder  hence the IB prefix  for your GUI components   IBOutlet is needed to associate properties in your application with components in IB  and IBAction is used to allow your methods to be associated with actions in IB     For example  suppose you define a button and label in IB   To dynamically change the value of the label by pushing the button  you will define an action and property in your app similar to   UILabel IBOutlet  myLabel  -  IBAction pushme  id sender    Then in IB you would connect myLabel with the label and connect the pushme method with the button   You need IBAction and IBOutlet for these connections to exist in IB

User · Answer

One of the top comments on this Question specifically asks   All the answers mention the same type of idea   but nobody explains why Interface Builder seems to work just the same if you DO NOT include IBAction IBOutlet in your source  Is there another reason for IBAction and IBOutlet or is it ok to leave them off    This question is answered well by NSHipster  IBAction https   nshipster com ibaction-iboutlet-iboutletcollection  ibaction  As early as 2004  and perhaps earlier   IBAction was no longer necessary for a method to be noticed by Interface Builder  Any method with the signature - void  name   id sender would be visible in the outlets pane  Nevertheless  many developers find it useful to still use the IBAction return type in method declarations to denote that a particular method is connected to by an action  Even projects not using Storyboards   XIBs may choose to employ IBAction to call out target   action methods   IBOutlet  https   nshipster com ibaction-iboutlet-iboutletcollection  iboutlet  Unlike IBAction  IBOutlet is still required for hooking up properties in code with objects in a Storyboard or XIB  An IBOutlet connection is usually established between a view or control and its managing view controller  this is often done in addition to any IBActions that a view controller might be targeted to perform by a responder   However  an IBOutlet can also be used to expose a top-level property  like another controller or a property that could then be accessed by a referencing view controller

User · Answer

IBAction and IBOutlets are used to hook up your interface made in Interface Builder with your controller  If you wouldn t use Interface Builder and build your interface completely in code  you could make a program without using them  But in reality most of us use Interface Builder  once you want to get some interactivity going in your interface  you will have to use IBActions and IBoutlets

User · Answer

The traditional way to flag a method so that it will appear in Interface Builder  and you can drag a connection to it  has been to make the method return type IBAction   However  if you make your method void  instead  IBAction is  define d to be void   and provide an  id  argument  the method is still visible   This provides extra flexibility  al    All 3 of these are visible from Interface Builder   - void  someMethod1  id  sender   - IBAction  someMethod2   - IBAction  someMethod3  id  sender    See Apple s Interface Builder User Guide for details  particularly the section entitled Xcode Integration

User · Answer

IBAction and IBOutlet are macros defined to denote variables and methods that can be referred to in Interface Builder   IBAction resolves to void and IBOutlet resolves to nothing  but they signify to Xcode and Interface builder that these variables and methods can be used in Interface builder to link UI elements to your code   If you re not going to be using Interface Builder at all  then you don t need them in your code  but if you are going to use it  then you need to specify IBAction for methods that will be used in IB and IBOutlet for objects that will be used in IB

User · Answer

when you use Interface Builder  you can use Connections Inspector to set up the events with event handlers  the event handlers are supposed to be the functions that have the IBAction modifier  A view can be linked with the reference for the same type and with the IBOutlet modifier

User · Answer

IBOutlet   It is a property   When the nib IB  file is loaded  it becomes part of encapsulated data which connects to an instance variable   Each connection is unarchived and reestablished    IBAction    Attribute indicates that the method is an action that you can connect to from your storyboard in Interface Builder      - Dynamic pattern IB - Interface Builder

User · Answer

An Outlet is a link from code to UI  If you want to show or hide an UI element  if you want to get the text of a textfield or enable or disable an element  or a hundred other things  you have to define an outlet of that object in the sources and link that outlet through the    interface object    to the UI element  After that you can use the outlet just like any other variable in your coding   IBAction     a special method triggered by user-interface objects  Interface Builder recognizes them    interface Controller     IBOutlet id textField     links to TextField UI object    -  IBAction doAction  id sender     e g  called when button pushed   For further information please refer Apple Docs

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