Xcode April 27, 2016 Wednesday

Connect the UI to Code

Theme

• The Weak keyword means that it's possible for this property to has no value (is nil) at some point in its life.

-@IBOutlet weak var Nametextfield:!

• An implicitly unwrapped optional, which are a optional type that would always has a value after the value is first set.

Target-action is a design in which one object sends a message to another object when a specific event occurs.

Create Outlets for UI Elements

To connect the text field to the Viewcontroller.swift code

A delegate is an object, which acts on behalf of, or in coordination with, another object.

Any object can serve as a delegate for another object as long as it conforms to the appropriate protocol.

Because Viewcontroller keeps a reference to the text field and you'll make Viewcontroller the text field ' s delegate.

Class viewcontroller:a href= "" uiviewcontroller/a, a href= "" uitextfielddelegate/a {

By adopting the protocol, you gave the Viewcontroller class the ability to identify itself as a uitextfielddelegate. This means your can set it as the delegate of the text field and implement some of its behavior to handle the text field ' s User input.

To set Viewcontroller as the delegate for Nametextfield

Handle the text field ' s user input through delegate callbacks.

Nametextfield.delegate = Self

The Uitextfielddelegate protocol contains optional methods, which means that you ' re not required to implement them.

When the user taps a text field, it automatically becomes first responder. In a app, the first responder is a object that's first on the line for receiving many kinds of app events, including Ke Y events, motion events, and action messages, among others. In other words, many of the events generated by the user is initially routed to the first responder.

As a result of the text field becoming first responder, IOS displays the keyboard and begins an editing session for that T Ext field. What a user types using this keyboard gets inserted into the text field.

When a user wants to finish editing the text field, the text field needs to resign its first-responder status. Because the text field would no longer is the active object in the app, events need to get routed to a more appropriate obj Ect.

This is the where your implementation of uitextfielddelegate methods comes in. You need to specify, the text field should resign its first-responder status, the user taps a button to end Editin G in the Text field. The Textfieldshouldreturn (_:) method, which gets called when the user taps Return (or in this case, done) o n the keyboard.

To implement the Uitextfielddelegate protocol method Textfieldshouldreturn (_:)　　

Xcode April 27, 2016 Wednesday