UserDefaults for simple values in iOS Swift - UI Render Trace

Component - UserDefaults for simple values

This UI component shows how to save and load simple values like text and numbers using UserDefaults in an iOS app. It has a text field to enter a name, a button to save it, and a label to display the saved name.

Widget Tree

UIViewController
├── UIView (main view)
│   ├── UITextField (for name input)
│   ├── UIButton (Save button)
│   └── UILabel (shows saved name)

The main view contains a text field at the top for typing a name, below it a button labeled 'Save Name', and below that a label that displays the saved name from UserDefaults.

Render Trace - 5 Steps

Step 1: UIViewController

Step 2: UITextField

Step 3: UIButton

Step 4: UILabel

Step 5: UserDefaults

State Change - Re-render

Trigger:User taps the 'Save Name' button after typing a name

Before

Label shows previously saved name or is empty; text field contains new name input

→

After

New name is saved to UserDefaults; label updates to show the new saved name

Re-renders:UILabel and UserDefaults data update; UITextField remains unchanged

UI Quiz - 3 Questions

What happens when the user taps the 'Save Name' button?

A The app closes immediately

B The typed name is saved to UserDefaults and label updates

C The text field clears but nothing is saved

D The label disappears

Key Insight

Using UserDefaults is a simple way to save small pieces of data like user preferences or text inputs. The UI should clearly show input controls and feedback labels so users know what is saved and loaded. Keeping the save action on a button tap gives users control over when data is stored.