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App Hangs in iOS: Causes, Code Fixes, and How to Spot Them

Published: · Last updated: · 5 min read
Don Peter
Cofounder and CTO, Appxiom

Ever tapped a button in your app and waited... and waited... until you started questioning your life choices?

Yeah, that's an app hang.

It's not a crash. It's worse. Your app doesn't explode, it just freezes. Quietly. Awkwardly. Like someone forgot their lines on stage and now the whole audience is staring.

App hangs are sneaky. They don't always show up in crash reports. But your users feel them. In the lags, the unresponsive screens, the moments when they swipe but nothing moves. And if it happens too often? That uninstall button starts looking real attractive.

But it doesn't have to be that way.

Let's fix the freeze before the curtain falls.

SOLVING FRAME RATE ISSUES AND APP HANGS IN SWIFTUI IOS APPS

Published: · Last updated: · 7 min read
Appxiom Team
Mobile App Performance Experts

Developing a smooth and responsive iOS app is crucial for providing a great user experience. Frame rate issues and app hangs can be frustrating for users and can lead to negative reviews and decreased app usage.

In this blog post, we will explore common causes of frame rate issues and app hangs in SwiftUI iOS apps and provide solutions and code examples to address them.

Understanding Frame Rate Issues

Frame rate issues occur when an app struggles to render frames at the desired rate, usually 60 frames per second (FPS) on most iOS devices. When the frame rate drops, animations become choppy, and the app feels less responsive. There are several common reasons for frame rate issues:

  • Inefficient View Updates: SwiftUI's declarative nature encourages frequent view updates. If not optimized, this can lead to excessive rendering and reduced frame rates.

  • Heavy Computation on the Main Thread: Performing CPU-intensive tasks on the main thread can block the UI, making the app feel unresponsive.

  • Large Images and Assets: Loading or rendering large images or assets can consume significant memory and processing power, leading to frame rate drops.

Solving Frame Rate Issues in SwiftUI

1. Optimize View Updates

You can optimize view updates by:

  • Using the .onAppear and .onDisappear modifiers to load data only when necessary.

  • Implementing the .id modifier to identify views uniquely and avoid unnecessary updates.

  • Reducing the complexity of SwiftUI view hierarchies.

Example:

struct ContentView: View {
var body: some View {
Text("Optimize your views")
.onAppear {
// Load data when the view appears
loadData()
}
}
}

2. Offload Heavy Computation

Move CPU-intensive tasks to background threads using DispatchQueue or Combine. Ensure that UI updates occur on the main thread.

Using DispatchQueue:

DispatchQueue.global().async {
// Perform heavy computation
let result = performHeavyComputation()

DispatchQueue.main.async {
// Update the UI on the main thread
self.resultLabel = result
}
}

Combine is a powerful framework for handling asynchronous and event-driven code in Swift. You can use Combine to perform background operations in SwiftUI seamlessly. In this example, we'll demonstrate how to use Combine to execute a background operation and update the SwiftUI view when the operation completes.

Let's say you want to fetch some data from a network API in the background and update your SwiftUI view when the data is ready. Here's a step-by-step guide:

  1. Import Combine in your SwiftUI view file:
import SwiftUI
import Combine
  1. Define a ViewModel to handle your data and background operations. Create an ObservableObject class that will hold your data and expose a publisher for notifying view updates.
class MyViewModel: ObservableObject {
@Published var data: [YourDataType] = [] // Replace YourDataType with the actual data type you're using
private var cancellables: Set<AnyCancellable> = []

func fetchData() {
// Simulate a background network request
fetchDataFromNetwork()
.receive(on: DispatchQueue.main) // Ensure updates are on the main thread
.sink { completion in
// Handle completion or errors if needed
} receiveValue: { [weak self] newData in
self?.data = newData
// Update the data when received
}
.store(in: &cancellables)
}

private func fetchDataFromNetwork() -> AnyPublisher<[YourDataType], Error> {
// Implement your network request logic here and return a Combine publisher
// For example, you can use URLSession's dataTaskPublisher
let url = URL(string: "https://your-api-url.com/data")!
return URLSession.shared.dataTaskPublisher(for: url)
.map(\.data)
.decode(type: [YourDataType].self, decoder: JSONDecoder())
.eraseToAnyPublisher()
}
}

Replace YourDataType with the actual type of data you're fetching from the network.

  1. Create a SwiftUI view that observes the changes in your ViewModel and triggers the background operation:
struct ContentView: View {
@ObservedObject private var viewModel = MyViewModel()

var body: some View {
VStack {
if viewModel.data.isEmpty {
Text("Loading...")
} else {
List(viewModel.data, id: \.self) { item in
// Display your data here
Text(item.name)
// Replace with your data properties
}
}
}
.onAppear {
viewModel.fetchData()
// Trigger the background operation when the view appears
}
}
}

In this SwiftUI view, the @ObservedObject property wrapper observes changes to the viewModel, and the onAppear modifier triggers the background operation by calling viewModel.fetchData() when the view appears.

Now, your SwiftUI view will fetch data from the network in the background using Combine and update the view when the data is ready, providing a smooth and responsive user experience.

3. Efficiently Manage Images and Assets

Load images lazily and use asset catalogs for managing image resources. Resize images to appropriate dimensions to reduce memory usage.

In SwiftUI, you can load images lazily using the AsyncImage view. AsyncImage allows you to load and display images asynchronously, which is especially useful for large images or images fetched from the network. Here's how you can use AsyncImage to load images lazily in SwiftUI:

import SwiftUI

struct LazyLoadingImageView: View {
let imageURL: URL
var body: some View {
AsyncImage(url: imageURL) { phase in
switch phase {
case .empty:
// Placeholder while loading (optional)
ProgressView()
case .success(let image):
// Successfully loaded image
image
.resizable()
.scaledToFit()
case .failure(_):
// Handle the failure (e.g., show an error message)
Image(systemName: "xmark.octagon")
.resizable()
.scaledToFit()
.foregroundColor(.red)
@unknown default:
// Handle other unknown states
Text("Unknown state")
}
}
}
}

In the code above:

  • AsyncImage is used to load the image asynchronously from the specified URL.

  • The closure inside AsyncImage receives a Phase parameter, which represents the current state of the image loading process.

  • In the .empty phase, you can display a placeholder (e.g., a ProgressView) to indicate that the image is being loaded.

  • In the .success phase, you can display the loaded image, making it resizable and scaling it to fit the available space.

  • In the .failure phase, you can handle the failure by displaying an error image or a message.

  • The @unknown default case is used to handle any unknown states that might be introduced in future SwiftUI versions.

To use the LazyLoadingImageView in your SwiftUI view, simply provide the URL of the image you want to load:

struct ContentView: View {
var body: some View {
LazyLoadingImageView(imageURL: URL(string: "https://example.com/image.jpg")!)
.frame(width: 200, height: 200)
}
}

Make sure to replace "https://example.com/image.jpg" with the actual URL of the image you want to load.

With AsyncImage, you can efficiently load and display images in a lazy manner, ensuring a smooth user experience, especially when dealing with large images or images from remote sources.

Addressing App Hangs

App hangs occur when the app becomes unresponsive for 250 milli seconds or more due to various reasons, such as blocking the main thread or network requests taking too long. Here are some strategies to prevent app hangs:

1. Use Background Threads for Network Requests

Perform network requests on background threads to avoid blocking the main thread. Combine or URLSession can be used for this purpose.

Example:

let cancellable = URLSession.shared.dataTaskPublisher(for: url)
.map(\.data)
.decode(type: MyModel.self, decoder: JSONDecoder())
.receive(on: DispatchQueue.main)
.sink(receiveCompletion: { _ in }) { data in
// Process data and update UI
}

2. Implement Error Handling

Handle errors gracefully, especially in asynchronous operations, to prevent app hangs and crashes.

do {
let result = try performRiskyOperation()
// Handle the result
} catch {
// Handle the error
}

3. Use Xcode Instruments and APM tools

Use Xcode's Instruments to profile your app's performance, identify bottlenecks, and monitor memory usage. Debugging tools like LLDB can help trace and fix specific issues causing frame rate issues and app hangs.

APM tools are a very much helpful in detecting frame rate issues and App Hangs. Appxiom is such an APM tool that helps in detecting these issues and provides all relevant data points to the developer to fix the issue.

Conclusion

Frame rate issues and app hangs can significantly impact the user experience of your SwiftUI iOS app. By optimizing view updates, offloading heavy computation, efficiently managing assets, and addressing app hangs through proper threading and error handling, you can create a smooth and responsive app that users will love.

Remember that performance optimization is an ongoing process. Regularly test your app on different devices and keep an eye on performance metrics to ensure a consistently great user experience.

REASONS FOR APP HANGS IN IOS AND HOW TO FIX THEM

Published: · Last updated: · 4 min read
Appxiom Team
Mobile App Performance Experts

App hangs or freezes are common issues faced by iOS users and can be frustrating for both developers and users. An app hang occurs when an application becomes unresponsive for more than 250 milliseconds, leading to a poor user experience.

In this blog post, we will explore some common reasons for app hangs in iOS and discuss effective solutions to fix them.

Reasons for App Hangs in iOS

1. Long-Running Tasks on the Main Thread

The main thread in iOS is responsible for handling user interactions and updating the user interface. Performing long-running tasks on the main thread can cause the app to freeze and become unresponsive. Examples of long-running tasks include network requests, database operations, or complex computations.

Solution: Move long-running tasks to background threads using Grand Central Dispatch (GCD) or Operation Queues. By doing so, the main thread remains free to handle user interactions, ensuring a smooth user experience.

Here's an example using GCD

DispatchQueue.global(qos: .background).async {
// Perform your long-running task here
DispatchQueue.main.async {
// Update UI on the main thread if necessary
}
}

2. Excessive CPU or Memory Usage

If an app consumes excessive CPU or memory resources, it can lead to poor performance and potential app hangs. Memory leaks, retain cycles, or inefficient resource management are common causes of high resource usage.

Solution: Use Instruments, a powerful profiling tool in Xcode, to analyze and optimize your app's CPU and memory usage. Address any memory leaks, properly release resources, and optimize algorithms to reduce resource consumption.

3. UI Blocking Operations

Performing operations that block the main thread can cause the app to hang. For instance, synchronous network requests or disk I/O operations can lead to unresponsiveness.

Solution: Utilize asynchronous APIs and techniques to prevent blocking the main thread. For network requests, use frameworks like Alamofire or URLSession with completion handlers or async/await for async APIs. For disk I/O, employ background queues or DispatchQueue.async.

4. Deadlocks and Race Conditions

Deadlocks occur when multiple threads are waiting for each other to release resources, resulting in a complete halt. Race conditions arise when multiple threads access shared resources simultaneously, leading to unpredictable behavior and app hangs.

Solution: Use synchronization techniques like locks, semaphores, or dispatch barriers to handle shared resources safely. Carefully review and analyze your code for potential deadlocks and race conditions. Utilize tools like Thread Sanitizer in Xcode to detect and fix such issues.

5. Infinite Loops

An infinite loop occurs when a section of code keeps executing indefinitely, preventing the app from responding.

Solution: Thoroughly review your code for any infinite loops and ensure appropriate loop termination conditions are in place. Use breakpoints and debugging tools to identify and fix such issues during development.

Using APM Tools to Detect and Identify App Hangs

In addition to following the aforementioned solutions, leveraging APM tools can be immensely helpful in identifying and diagnosing the root cause of app hangs. Two popular APM tools for iOS are Firebase and Appxiom.

1. Firebase Performance Monitoring

Firebase Performance Monitoring is a comprehensive APM tool provided by Google. It allows you to gain insights into your app's performance, including metrics related to app hangs, slow rendering, network requests, and more.

2. Appxiom

Appxiom is another powerful APM tool specifically designed for iOS and Android applications. It offers deep insights into app performance, including identifying bottlenecks, detecting crashes, and diagnosing app hangs.

Conclusion

App hangs in iOS can be caused by various factors such as long-running tasks on the main thread, excessive CPU or memory usage, UI blocking operations, deadlocks, race conditions, and infinite loops. By understanding these reasons and implementing the suggested solutions, you can significantly improve your app's responsiveness and provide a better user experience.

Additionally, by utilizing APM tools like Firebase and Appxiom, you can detect and identify the root cause of app hangs more effectively. These tools offer detailed insights, performance metrics, and real-time monitoring to help you optimize your app's performance and address hang-related issues promptly.

Remember to test your app thoroughly on different devices and iOS versions to ensure its stability and responsiveness. Regularly profiling and optimizing your app's performance will help you catch and resolve potential hang issues early in the development cycle.

By following best practices, utilizing appropriate tools, and adopting efficient coding techniques, you can mitigate app hangs and deliver a seamless experience to iOS users.

Happy coding!

FRAME RATE ISSUES IN FLUTTER APPS AND HOW TO SOLVE THEM

Published: · Last updated: · 4 min read
Appxiom Team
Mobile App Performance Experts

Flutter, Google's open-source UI development framework, has gained immense popularity among developers for its cross-platform capabilities and smooth performance. However, like any software development framework, Flutter apps may encounter frame rate issues that can impact user experience.

In this blog, we will explore the common causes of frame rate issues in Flutter apps and provide effective solutions to mitigate them.

Understanding Frame Rate Issues in Flutter Apps

The frame rate of a Flutter app refers to the number of frames or screen updates displayed per second. The standard frame rate for smooth user experience is 60 frames per second (fps). If an app fails to achieve this frame rate consistently, it can result in stuttering animations, sluggish responsiveness, and an overall degraded user experience.

In Android, frame rate issues may manifest as App Not Responding (ANR) if the UI Thread gets blocked for 5000 milliseconds or more. If the UI Frames take 700 milliseconds or more to render it is a Frozen Frame situation and if it takes 16 milliseconds or more it is a Slow Frame situation.

In iOS, if the UI Thread is stuck for 250 milliseconds or more it is an App Hang, also called App Freeze, situation.

Common Causes of Frame Rate Issues

1. Expensive Widget Rebuilds

class MyExpensiveWidget extends StatelessWidget {
final ExpensiveData data;

const MyExpensiveWidget({required this.data});

@override
Widget build(BuildContext context) {
// Widget build logic that might be expensive
return ...;
}
}

To optimize widget rebuilds, use const constructors whenever possible. By using const, Flutter can efficiently skip the widget rebuild if the constructor parameters haven't changed.

2. Inefficient Animations

class MyAnimationWidget extends StatefulWidget {
@override
_MyAnimationWidgetState createState() => _MyAnimationWidgetState();
}

class _MyAnimationWidgetState extends State<MyAnimationWidget>
with SingleTickerProviderStateMixin {
late AnimationController _controller;
late Animation<double> _animation;

@override
void initState() {
super.initState();
_controller = AnimationController(
duration: const Duration(milliseconds: 500),
vsync: this,
);
_animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
_controller.forward();
}

@override
void dispose() {
_controller.dispose();
super.dispose();
}

@override
Widget build(BuildContext context) {
return AnimatedBuilder(
animation: _animation,
builder: (context, child) {
// Widget build logic using the animation value
return ...;
},
);
}
}

To optimize animations, use lightweight animations like Tween animations instead of heavy ones like Hero animations. Properly dispose of animation controllers to release resources and avoid unnecessary computations. Implement animation caching techniques, such as pre-loading and reusing animations, to reduce performance impact.

3. Inadequate Caching and Data Fetching

class MyDataFetcher {
static final Map<String, dynamic> _cache = {};

static Future<dynamic> fetchData(String url) async {
if (_cache.containsKey(url)) {
return _cache[url];
} else {
final response = await http.get(Uri.parse(url));
final data = json.decode(response.body);
_cache[url] = data;
return data;
}
}
}

To optimize caching and data fetching, implement proper caching strategies. Utilize Flutter's built-in caching mechanisms, such as cached_network_image, to minimize repeated image downloads. Implement pagination techniques to fetch data incrementally instead of in one large chunk.

4. Simplify Layouts

class MyComplexLayout extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: [
Expanded(
child: Row(
children: [
Flexible(child: Container()),
Flexible(child: Container()),
],
),
),
Expanded(
child: Container(),
),
],
),
);
}
}

To simplify layouts, minimize nested layouts and unnecessary constraints. Use appropriate layout widgets based on specific requirements. Avoid excessive use of Expanded and Flexible widgets when other layout techniques like SizedBox or AspectRatio can achieve the desired results.

Use App Performance Monitoring (APM) Tools

Monitoring the frame rate of a Flutter app is crucial for maintaining optimal performance and delivering a smooth user experience. APM tools provide valuable insights into the app's rendering performance, allowing developers to identify and address frame rate issues effectively.

Two widely used tools for frame rate monitoring in Flutter are Firebase Performance Monitoring and Appxiom.

Conclusion

Frame rate issues in Flutter apps can negatively impact the user experience, leading to reduced engagement and user satisfaction. By optimizing widget rebuilds, animations, caching and data fetching, as well as simplifying layouts, developers can ensure a smooth and responsive UI.

Remember to profile your app, optimize animations, simplify layouts, and follow best practices to address frame rate issues effectively. Use APM tools to continuously monitor app performance including frame rate issues. With careful attention to performance optimization, Flutter can deliver exceptional user experiences across various platforms.

PERFORMANCE TESTING OF IOS APPS

Published: · Last updated: · 4 min read
Appxiom Team
Mobile App Performance Experts

Performance testing is a critical aspect of iOS app development. It ensures that the app performs optimally, providing a seamless user experience. With millions of apps available in the App Store, it is imperative that an iOS app must perform well to succeed.

In this blog, we will explore what iOS app performance testing is, the best practices to follow, and the tools available.

What is iOS App Performance Testing?

iOS app performance testing is the process of testing an application's performance and behavior on iOS devices. The testing process includes evaluating the app's response time, speed, stability, scalability, and resource utilization. The goal of iOS app performance testing is to identify any performance issues before the app is released to the public.

What to test?

  • Memory usage including memory leaks, abnormal memory usage, memory spikes.

  • Battery drain

  • CPU usage

  • Network call performance issues, Error status codes in responses, delayed calls, duplicate calls.

  • App Hang

  • Screen responsiveness

  • User flow and logic

Steps in iOS App Performance Testing

  • Define Test Objectives - The first step in iOS app performance testing is to define the test objectives. This includes identifying the target audience, user scenarios, and performance goals.

  • Identify Performance Metrics - The next step is to identify the performance metrics that need to be tested. This includes response time, speed, stability, scalability, and resource utilization.

  • Create Test Environment - The test environment should be created to simulate real-life scenarios. This includes configuring the hardware and software components, network conditions, and device settings.

  • Develop Test Plan - A detailed test plan should be developed, outlining the test scenarios, test cases, and expected results.

  • Execute Test Plan - The test plan should be executed as per the defined scenarios, and the app's performance should be evaluated under different conditions.

  • Analyze Test Results - The test results should be analyzed to identify performance issues and bottlenecks.

  • Optimize App Performance - Based on the test results, the app's performance should be optimized to ensure that it meets the performance goals and objectives.

Tools for iOS App Performance Testing

  • Xcode Instruments - Xcode Instruments is a powerful tool that can be used for iOS app performance testing. It provides a wide range of profiling and debugging tools that can help identify and resolve performance issues.

  • Charles Proxy - Charles Proxy is a tool that can be used to monitor network traffic, including HTTP and SSL traffic. It can be used to test the app's performance under different network conditions.

  • XCTest - XCTest is an automated testing framework provided by Apple for testing iOS apps. It can be used to create automated performance tests.

  • Firebase Test Lab - Firebase Test Lab is a cloud-based testing platform that provides a wide range of testing capabilities, including performance testing.

  • BrowserStack - Cloud based testing platform with a range of features to identify and debug issues while testing.

  • Appxiom - SaaS platform that reports performance issues and bugs in iOS apps in real time. It detects Memory issues, screen responsiveness, crashes, rendering issues, network call issues over HTTP and HTTPS and much more in development, testing and live phases of the app.

Best Practices for iOS App Performance Testing

  • Test Early and Often - iOS app performance testing should be an integral part of the development process, and testing should be done early and often.

  • Use Real Devices - Testing should be done on real devices to simulate real-life scenarios accurately.

  • Define Realistic Test Scenarios - Test scenarios should be defined based on real-life scenarios to ensure that the app's performance is tested under realistic conditions.

  • Use Automated Testing - Automated testing should be used to reduce the testing time and improve accuracy.

  • Monitor App Performance - App performance should be monitored continuously to identify any performance issues and bottlenecks.

  • Collaborate with Developers - Collaboration between testers and developers can help identify and resolve performance issues early in the development process.

Conclusion

iOS app performance testing ensures that the app performs optimally, providing a seamless user experience. By following best practices and using the right tools, iOS app developers can identify and resolve performance issues early in the development process, resulting in a high-quality app that meets the user's expectations. It is essential to test the app's performance under different conditions to ensure that it performs well under all circumstances. Therefore, app performance testing should be an integral part of the iOS app development process.

WHY MOBILE APP TESTERS AND DEVELOPERS SHOULD USE APM TOOLS FOR PERFORMANCE MONITORING.

Published: · Last updated: · 2 min read
Appxiom Team
Mobile App Performance Experts

Performance monitoring and continues bug monitoring are critical parts of the Mobile App development lifecycle. As mobile devices become more powerful and users expect more from their apps, it is essential to ensure that apps are performing well and are free of bugs. One way to achieve this is by using Application Performance Management (APM) tools.

APM tools are designed to help mobile app testers and developers detect and diagnose performance issues and bugs in their apps. These tools provide a wide range of information about an app's performance, including memory usage, CPU usage, network activity, and more. This information can be used to identify bottlenecks, memory leaks, and other issues that can negatively impact an app's performance.

One of the main benefits of using APM tools is that they can help app developers and testers find and fix performance issues before they become a problem for users. By identifying issues early in the development process, teams can make changes to improve performance and ensure that the app is stable and reliable. This can help reduce the number of crashes and improve the overall user experience.

Another benefit of using APM tools is that they can help developers and testers understand how users are interacting with their apps. This can be especially useful for understanding how different user segments are interacting with the app, which can help teams optimize the user experience and make improvements that will have the biggest impact.

In short, APM tools are an essential tool for mobile app testers and developers. They help teams identify and fix performance issues and bugs, improve the user experience, and ensure that apps are stable and reliable. By using APM tools, teams can deliver better quality apps and create a more positive user experience.

Visit appxiom.com to know more about how Appxiom can help you with monitoring performance and bugs in mobile apps.

HOW TO DETECT APP HANGS IN IOS APPS, AND FIX THEM.

Published: · Last updated: · 4 min read
Don Peter
Cofounder and CTO, Appxiom

One major objective for any app developer is to make sure that their iOS app is smooth and responsive. So, how does one make sure the app is responsive? The rule of thumb is that an application should be able to react to user inputs and touches within 250ms.

If the response time is above 250 ms then the delay becomes apparent and will be noticeable to the app user. iOS documentation categorizes any app response delay that persists for more than 250 ms as App hang.

What developers need is a proper way to identify and fix App hangs. XCode organizer and bug reporting tools like MetricKit and Appxiom report App hangs. Reports generated by xcode organizer and MetricKit are not real-time and they also miss App Hangs at times.

Appxiom reports App hangs that occur in the application in real-time and supports development, Test Flight and App Store builds. Because the reports are real-time, most App Hang situations will be captured.

Analyzing an App Hang Report

Here are some of the metrics needed for deeper analysis from an App hang report generated by Appxiom,

  • Top iOS versions affected.

  • Top device models affected.

  • First app version where the issue is detected.

  • Number of occurrences of the issue.

  • Total time for which the app was unresponsive.

  • Stack trace to identify the point of hang.

Appxiom provides App hang issue reports with these metrics.

Top OS versions, Device models and countries where App hang was reportedNumber of Devices and total occurrence count of App hang issuePrevious app versions, if any, where the same App hang issue was reportedIn most cases the stack trace provided with the issue should give indication of where the root cause lies.

Stack-trace indicating the point of origin of App hang issueThere could be situations where stack trace alone might not be sufficient. This is when the rest of the metrics help.

Look for patterns like the top OS versions, device models and the app version where this issue first occurred in the issue report. Occurrences count of the issue will provide a sense of how severe the issue is. Using the combination of these, developers will be able to prioritize and create the test device configuration to reproduce the issue.

Next step is to retrace how the user interacted with the app when the issue occurred. Activity trail, which is a chronologically ordered list of events that happened prior to the App hang which is provided with each App hang issue report in Appxiom dashboard. It will have events like the lifecycle of the different viewcontrollers, network changes and state changes of the app along with custom events that are set by the developer.

Activity trail listing events that occurred prior to App hang issue.This will help developers to retrace the app events to identify and reproduce the issue.

How to avoid App Hang situations.

Now that we know how to detect and fix App hangs, let us explore ways to prevent App hangs.

In order to achieve this the main thread of the app should be free from running intensive operations as the application gets frozen when the main thread is stuck.

Now what this means is, execute only tasks that interact with the user interface in the main thread i.e UIKit, AppKit, or SwiftUI based tasks. So how does one execute other long running tasks? Use background threads directly or either through the operation queue or through the Grand Central Dispatch queue to execute such operations.

Let us take the example of a simple HTTP(s) request and using its response data to update a tableview in the app. It is not just the HTTP(s) request that we execute in the separate thread, but de-serializing the JSON object from the response data should be executed outside of the main thread as well. Only the actual tableview update code needs to be executed in the main thread.

Following this coding practice will lower the possibility of App hang issues in your application.

Appxiom is available for Objective-C and Swift in iOS and watchOS, and for Java and Kotlin in Android. Click here to get started.