What is the difference between IBOutlet and IBAction in iOS ?

IBAction and IBOutlet are macros defined to denote variables and methods that can be referred to in Interface Builder.
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​IBAction and IBOutlets are used to hook up your interface made in Interface Builder with your controller

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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.

IBOutlet 

Special instance variable that references another object. A message can be sent through an outlet. Interface Builder recognizes them. An IBOutlet is for hooking up a property to a view when designing your XIB. 

-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.

-An IBOutlet is for hooking up a property to a view when designing your XIB

-An IBOutlet lets you reference the view from your controller code


IBAction 

A special method triggered by user-interface objects. Interface Builder recognizes them. An IBAction is for hooking a method (action) up to a view when designing your XIB.

-IBAction resolves to void .

- An IBAction is for hooking a method (action) up to a view when designing your XIB.

An IBAction lets the view call a method in your controller code when the user interacts with the view.