10 iOS Logging Best Practices

Logging is an essential part of any iOS application. It helps developers to debug and troubleshoot issues quickly. Logging also helps to track user activities and identify potential issues.

However, logging can also be a source of security vulnerabilities if not done properly. To ensure that your application is secure and your logs are useful, it is important to follow best practices for logging in iOS. In this article, we will discuss 10 iOS logging best practices that you should follow.

1. Use NSLog() for debugging, but not in production code

NSLog() is a simple logging function that prints out messages to the console. It’s great for debugging, but it can be slow and inefficient in production code because it has to write to the console every time it’s called.

Instead of using NSLog(), use other logging frameworks such as CocoaLumberjack or XCGLogger. These frameworks are more efficient and provide better performance than NSLog(). They also allow you to customize your log levels so you can easily filter out unnecessary logs.

2. Logging should be lightweight and non-blocking

Logging can be a resource-intensive process, and if it’s done too often or in the wrong places, it can slow down your app.

To ensure that logging is lightweight and non-blocking, you should use asynchronous logging methods whenever possible. This means using APIs like NSLog() instead of print(), which will log messages without blocking the main thread. Additionally, you should avoid logging large objects such as images or videos, as this can cause performance issues. Finally, make sure to only log what is necessary for debugging purposes; don’t log every action taken by the user, as this can quickly become overwhelming.

3. Always log the method name and line number

When you log an error, it’s important to include the method name and line number so that you can quickly identify where the issue occurred. This makes debugging much easier because you don’t have to search through your codebase for the source of the problem.

Logging the method name and line number also helps when troubleshooting issues in production. If a customer reports an issue, you can look at their logs and quickly pinpoint the exact location of the bug. This saves time and ensures that bugs are fixed as quickly as possible.

4. Use logging levels to control verbosity

Logging levels allow you to control the amount of information that is logged. For example, if you set your logging level to “error” then only errors will be logged. This helps keep your logs clean and organized so that it’s easier to find what you’re looking for.

Logging levels also help you prioritize which messages are most important. If you have a critical issue in production, setting the logging level to “fatal” will ensure that only the most serious issues are logged. This makes it much easier to quickly identify and address any problems.

5. Don’t use breakpoints for logging

Breakpoints are a great way to pause the execution of your code and inspect variables, but they should not be used for logging. Breakpoints can cause unexpected behavior in your app, such as freezing or crashing, which can make it difficult to debug issues. Additionally, breakpoints can slow down the performance of your app, making it less responsive.

Instead of using breakpoints for logging, use NSLog() statements. This is a much more reliable method that won’t interfere with the performance of your app. You can also use third-party libraries like CocoaLumberjack to help you log messages more efficiently.

6. Use a custom logger class

A custom logger class allows you to easily control the logging level, which is important for debugging and troubleshooting. It also makes it easier to add additional log statements as needed without having to modify existing code.

A custom logger class should include methods for setting the logging level, writing messages to the console, and writing errors to a file. Additionally, it should be able to handle different types of data such as strings, numbers, objects, etc. This will make it easier to debug issues quickly and accurately.

7. Avoid logging sensitive information

Logging sensitive information can be a security risk, as it could potentially be accessed by malicious actors. Additionally, logging too much data can slow down your app and cause performance issues.

To avoid these risks, iOS developers should only log the necessary information needed to debug their application. This includes things like error messages, stack traces, and other debugging-related information. Developers should also make sure that they are not logging any personal or confidential information, such as passwords, credit card numbers, etc.

8. Add context to your logs

When you’re debugging an issue, it’s often difficult to tell what the root cause is without having enough context.

Adding context to your logs can help you quickly identify and isolate issues. For example, if you log a message with the user ID, device type, OS version, etc., then you’ll be able to easily pinpoint which users are affected by a particular bug or issue.

You should also consider adding timestamps to your logs so that you can track how long certain operations take. This will give you valuable insight into performance bottlenecks in your code.

9. Use logging macros instead of string formatting

Logging macros are pre-defined functions that allow you to quickly and easily log messages with the correct formatting. This saves time, as you don’t have to manually format each message before logging it. It also ensures consistency in your logs, which makes them easier to read and interpret.

Using logging macros also helps reduce errors caused by typos or incorrect formatting. For example, if you use a macro for logging an error, you can be sure that the message will always include the necessary information (such as the file name, line number, etc.). This makes debugging much easier.

10. Consider using third party libraries

Third party libraries provide a wide range of features that can help you log more efficiently and effectively. For example, they often offer advanced logging capabilities such as filtering, formatting, and customizing logs to make them easier to read and analyze. They also allow for remote logging, which is especially useful if you need to debug an issue on a device that isn’t connected to your development environment. Finally, third party libraries are typically well-maintained and updated regularly, so you don’t have to worry about maintaining your own codebase.