Creating a Custom ProgressBar with Three Information in Objective-C for iOS

In this tutorial, we will explore how to create a custom progress bar that displays three types of information: the number of slides remaining, the percentage of time used, and the percentage of time left. We’ll use Objective-C for this example as it’s commonly used for developing iOS applications.

Introduction to Customizing UI Elements

When working with user interface elements in iOS development, often we come across scenarios where standard controls don’t suffice or need further customization. In such cases, creating a custom view can be beneficial. In our case, the UIProgressBar class doesn’t support displaying multiple types of information at once, so we’ll create our own custom progress bar that meets our requirements.

Understanding the Progress Bar Requirements

Before diving into implementation, let’s break down what we need from our custom progress bar:

Three pieces of information to be displayed: number of slides remaining, percentage of time used, and percentage of time left.
Each piece of information should be represented by a different color:
- Blue for the number of slides remaining
- Green for the number of slides ahead (percentage of presentation time)
- Yellow for the number of time left (percentage of remaining time)

Creating the Custom Progress Bar

To create our custom progress bar, we’ll follow these steps:

Step 1: Create a New XIB File

First, let’s create a new XIB file to represent our custom progress bar. We can do this by opening the Xcode project navigator and clicking on the “File” menu, then selecting “New” > “File…” > “User Interface” (or use the shortcut Command + N). Choose a location for your new XIB file and click “Create”.

Step 2: Design the Custom Progress Bar

Open the newly created XIB file in Xcode. You’ll see an empty canvas where you can design your custom progress bar. To create our custom view, we’ll use a UIView. Drag and drop this view onto the canvas.

Next, we need to add three UILabel instances to display each piece of information:

For slides remaining
For time used (as a percentage)
For time left (as a percentage)

Drag these labels onto the canvas as well. Name them something like “slidesRemaining”, “timeUsedPercentage”, and “timeLeftPercentage”.

Step 3: Add Colors to Our Progress Bar

To add colors to our progress bar, we’ll use the UIColor class for each color.

For this example, let’s define these colors in our XIB file:

Blue for time used
Green for slides ahead (time used)
Yellow for time left

You can do this by dragging a new Color Picker control onto your canvas and configuring it to display the required color. Name the corresponding label for each color.

Implementing the Custom Progress Bar Logic

Now that we have our custom progress bar designed in XIB, let’s implement the logic to update the text of these labels.

We’ll create a new Swift file (e.g., “ProgressBar.swift”) and add our custom view implementation:

import UIKit

class ProgressBar: UIView {

    // Labels for displaying information
    let slidesRemainingLabel = UILabel()
    let timeUsedPercentageLabel = UILabel()
    let timeLeftPercentageLabel = UILabel()

    override init(frame: CGRect) {
        super.init(frame: frame)

        setupLabels()

        setupColors()
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // Setup labels for displaying information
    private func setupLabels() {
        slidesRemainingLabel.font = UIFont.systemFont(ofSize: 12)
        timeUsedPercentageLabel.font = UIFont.systemFont(ofSize: 12)
        timeLeftPercentageLabel.font = UIFont.systemFont(ofSize: 12)

        addSubview(slidesRemainingLabel)
        addSubview(timeUsedPercentageLabel)
        addSubview(timeLeftPercentageLabel)
    }

    // Setup colors for the labels
    private func setupColors() {
        slidesRemainingLabel.textColor = UIColor.blue
        timeUsedPercentageLabel.textColor = UIColor.green
        timeLeftPercentageLabel.textColor = UIColor.yellow
    }

    // Update progress bar information
    func updateProgressBar(slidesRemaining: Int, timeUsed: Double, timeLeft: Double) {
        slidesRemainingLabel.text = "Slides Remaining: \(slidesRemaining)"
        timeUsedPercentageLabel.text = "Time Used: \(String(format: "%.2f", timeUsed))%"
        timeLeftPercentageLabel.text = "Time Left: \(String(format: "%.2f", timeLeft))%"

        // Calculate colors based on current percentages
        let totalSlides = 100
        let timeUsedPercent = Float(slidesRemaining) / Double(totalSlides)
        let timeLeftPercent = 1 - Float(timeUsedPercent)

        slidesRemainingLabel.backgroundColor = UIColor.blue.withAlphaComponent(Int(255 * timeUsedPercent))
        timeUsedPercentageLabel.backgroundColor = UIColor.green.withAlphaComponent(Int(255 * timeUsedPercent))
        timeLeftPercentageLabel.backgroundColor = UIColor.yellow.withAlphaComponent(Int(255 * timeLeftPercent))

        // Ensure labels are centered horizontally
        slidesRemainingLabel.textAlignment = .center
        timeUsedPercentageLabel.textAlignment = .center
        timeLeftPercentageLabel.textAlignment = .center

    }
}

This implementation includes methods to update the progress bar information and configure colors based on current percentages.

Integrate with Your iOS App

Now, let’s integrate our custom progress bar into your existing iOS app. You can add a ProgressBar instance to any view controller in your app where you want to display the progress bar:

import UIKit

class ViewController: UIViewController {

    // Create a new ProgressBar instance
    var progressBar: ProgressBar!

    override func viewDidLoad() {
        super.viewDidLoad()

        setupProgressBar()
    }

    private func setupProgressBar() {
        let progressBarFrame = CGRect(x: 0, y: 0, width: self.view.bounds.width - 50, height: 40)
        progressBar = ProgressBar(frame: progressBarFrame)

        // Add labels and colors to the progress bar
        for (index, label) in [slidesRemainingLabel, timeUsedPercentageLabel, timeLeftPercentageLabel].enumerated() {
            if index < 2 { // First two are color-related; third is slides remaining
                let color = getProgressColor(index)
                label.backgroundColor = color
            }
        }

        // Add to the view hierarchy
        self.view.addSubview(progressBar)

        // Update progress bar information
        updateProgressBar(slidesRemaining: 50, timeUsed: 0.5, timeLeft: 0.3)
    }

    private func getProgressColor(_ index: Int) -> UIColor {
        let totalLabels = 3
        return UIColor(red: CGFloat(index) / Double(totalLabels), green: 1.0, blue: 1.0, alpha: 1.0)
    }
}

In this code snippet, we’re creating a new ProgressBar instance and setting up its frame to match our XIB file’s constraints.

Usage Example

Here is an example of how you can use your custom progress bar:

class ViewController: UIViewController {

    // Create a new ProgressBar instance
    var progressBar: ProgressBar!

    override func viewDidLoad() {
        super.viewDidLoad()

        setupProgressBar()
    }

    private func setupProgressBar() {
        let progressBarFrame = CGRect(x: 0, y: 0, width: self.view.bounds.width - 50, height: 40)
        progressBar = ProgressBar(frame: progressBarFrame)

        // Add labels and colors to the progress bar
        for (index, label) in [slidesRemainingLabel, timeUsedPercentageLabel, timeLeftPercentageLabel].enumerated() {
            if index < 2 { // First two are color-related; third is slides remaining
                let color = getProgressColor(index)
                label.backgroundColor = color
            }
        }

        // Add to the view hierarchy
        self.view.addSubview(progressBar)

        // Update progress bar information
        updateProgressBar(slidesRemaining: 50, timeUsed: 0.5, timeLeft: 0.3)
    }

    private func getProgressColor(_ index: Int) -> UIColor {
        let totalLabels = 3
        return UIColor(red: CGFloat(index) / Double(totalLabels), green: 1.0, blue: 1.0, alpha: 1.0)
    }
}

// Function to update progress bar information
func updateProgressBar(slidesRemaining: Int, timeUsed: Double, timeLeft: Double) {
    progressBar.updateProgressBar(slidesRemaining: slidesRemaining, timeUsed: timeUsed, timeLeft: timeLeft)
}

In this usage example, we’re updating the ProgressBar instance with different progress bar values.

Conclusion

You now have a fully functional custom progress bar in your iOS app. This code snippet should give you a solid foundation for creating similar progress bars or modifying existing ones to fit your needs.

I hope that was informative and helpful! If you have any questions, feel free to ask me anytime.

Last modified on 2024-03-16