Why Image view (system and asset) in iOS Swift? - Purpose & Use Cases

The Big Idea

Discover how a simple image view saves you hours of tedious work and makes your app shine!

The Scenario

Imagine you want to show pictures in your app, like a photo or an icon. Without image views, you would have to draw each picture by hand pixel by pixel, which is like painting a picture with tiny dots one by one.

The Problem

This manual way is very slow and mistakes happen easily. If you want to change the picture, you must redo all the drawing. It's hard to keep pictures the same size or make them look good on different screens.

The Solution

Using image views lets you simply tell the app which picture to show, either from the system icons or your own saved images. The system handles drawing, resizing, and showing the image perfectly on any device.

Before vs After

✗ Before

// Manually drawing an image is complex and long
// No simple code snippet for this
// Imagine drawing pixels one by one

✓ After

let imageView = UIImageView(image: UIImage(systemName: "star.fill"))
view.addSubview(imageView)

What It Enables

You can quickly add beautiful images and icons that adapt to different screen sizes and styles without extra work.

Real Life Example

Think of a weather app showing sun or rain icons using system images, or a photo gallery app displaying your saved pictures easily with asset images.

Key Takeaways

Manual image drawing is slow and error-prone.

Image views let you display system or asset images easily.

This makes your app look professional and work well on all devices.

Practice

1. What is the correct way to create an image view that displays an image named "logo" from your app's assets?

easy

A. UIImageView(image: UIImage(named: "logo"))

B. UIImageView(image: UIImage(systemName: "logo"))

C. UIImageView(named: "logo")

D. UIImageView(systemName: "logo")

Solution

1. Step 1: Understand UIImageView initialization

   UIImageView is initialized with a UIImage object, not a string name directly.

2. Step 2: Load image from assets correctly

   Use UIImage(named:) to load an image from app assets by name.

3. Final Answer:

   UIImageView(image: UIImage(named: "logo")) -> Option A

4. Quick Check:

   Load asset image with UIImage(named:) = D [OK]

Hint: Use UIImage(named:) for asset images, not systemName [OK]

Common Mistakes:

• Using UIImage(systemName:) for asset images
• Passing string directly to UIImageView initializer
• Confusing UIImageView(named:) which doesn't exist

2. Which of the following is the correct syntax to create a system image view with the icon named "star.fill"?

easy

A. UIImageView(image: UIImage(named: "star.fill"))

B. UIImageView(systemName: "star.fill")

C. UIImageView(image: UIImage(systemName: "star.fill"))

D. UIImageView(image: "star.fill")

Solution

1. Step 1: Identify system image loading method

   System icons are loaded using UIImage(systemName:).

2. Step 2: Initialize UIImageView with system image

   Pass UIImage(systemName: "star.fill") to UIImageView's image parameter.

3. Final Answer:

   UIImageView(image: UIImage(systemName: "star.fill")) -> Option C

4. Quick Check:

   System image uses UIImage(systemName:) = B [OK]

Hint: Use UIImage(systemName:) for system icons only [OK]

Common Mistakes:

• Using UIImage(named:) for system icons
• Trying to initialize UIImageView with systemName directly
• Passing string instead of UIImage object

3. What will be the result of this Swift code snippet?

let imageView = UIImageView(image: UIImage(systemName: "heart.fill"))
imageView.tintColor = .red

medium

A. An image view showing a red filled heart system icon

B. An image view showing a heart icon with default color (black)

C. A runtime error because tintColor cannot be set

D. An empty image view with no image displayed

Solution

1. Step 1: Load system image "heart.fill"

   UIImage(systemName: "heart.fill") loads a filled heart icon.

2. Step 2: Set tintColor to red

   Setting imageView.tintColor to .red colors the system icon red.

3. Final Answer:

   An image view showing a red filled heart system icon -> Option A

4. Quick Check:

   System icon + tintColor = colored icon [OK]

Hint: System icons respect tintColor for color changes [OK]

Common Mistakes:

• Assuming system icons ignore tintColor
• Confusing asset images with system icons for tinting
• Expecting default black color after setting tintColor

4. Identify the error in this Swift code that tries to display a system image "bell" in an image view:

let imageView = UIImageView(image: UIImage(named: "bell"))
imageView.tintColor = .blue

medium

A. The code is correct and will display a blue bell icon

B. UIImageView does not have a tintColor property

C. The image name "bell" is invalid for assets

D. UIImage(named:) cannot load system images like "bell"

Solution

1. Step 1: Check image loading method

   UIImage(named:) loads images from app assets, not system icons.

2. Step 2: Recognize system image loading requirement

   System images like "bell" must be loaded with UIImage(systemName:).

3. Final Answer:

   UIImage(named:) cannot load system images like "bell" -> Option D

4. Quick Check:

   System images need UIImage(systemName:) = A [OK]

Hint: Use UIImage(systemName:) for system icons, not UIImage(named:) [OK]

Common Mistakes:

• Using UIImage(named:) for system icons
• Assuming tintColor works without correct image loading
• Thinking UIImageView lacks tintColor property

5. You want to display a system image "trash" in red color and an asset image "icon" in your app. Which code snippet correctly creates both UIImageViews with the right images and colors?

hard

A. let trashView = UIImageView(image: UIImage(systemName: "trash"))
trashView.tintColor = .red
let iconView = UIImageView(image: UIImage(systemName: "icon"))

B. let trashView = UIImageView(image: UIImage(systemName: "trash"))
trashView.tintColor = .red
let iconView = UIImageView(image: UIImage(named: "icon"))

C. let trashView = UIImageView(image: UIImage(named: "trash"))
trashView.tintColor = .red
let iconView = UIImageView(image: UIImage(systemName: "icon"))

D. let trashView = UIImageView(image: UIImage(named: "trash"))
trashView.tintColor = .red
let iconView = UIImageView(image: UIImage(named: "icon"))

Solution

1. Step 1: Load system image "trash" correctly

   Use UIImage(systemName: "trash") for system icon and set tintColor to red.

2. Step 2: Load asset image "icon" correctly

   Use UIImage(named: "icon") for asset image without tintColor.

3. Final Answer:

   let trashView = UIImageView(image: UIImage(systemName: "trash"))\ntrashView.tintColor = .red\nlet iconView = UIImageView(image: UIImage(named: "icon")) -> Option B

4. Quick Check:

   System image + tintColor, asset image with UIImage(named:) = C [OK]

Hint: System images use systemName + tintColor; assets use named without tint [OK]

Common Mistakes:

• Mixing UIImage(named:) and UIImage(systemName:) incorrectly
• Setting tintColor on asset images expecting color change
• Using systemName for asset images