In mobile app development, logs and crash reports are often the most direct clues for identifying issues. Many times, users only report that the app crashed, and the real cause can only be found in device logs or crash reports.
Relying solely on user descriptions or simple issue reproduction makes the troubleshooting process inefficient. Therefore, in actual development and testing, multiple tools are typically combined to view iOS device logs and crash reports.
Sources of iOS Logs and Crash Reports
In iOS devices, the system automatically records various types of log data, including:
- Application runtime logs
- System logs
- Crash reports
- Performance diagnostic data
When an app crashes, the system generates a crash report file, usually saved in the device’s system log directory.
This data can be read through development tools or device management tools.
First Method: View Device Logs via Xcode
During the development phase, the most common method is to view logs via Xcode.
The basic process is as follows:
- Connect the iPhone using a data cable
- Open Xcode
- Go to Devices and Simulators
- Select the device and click View Device Logs
In this interface, you can see a list of the device’s crash logs.
After clicking on a log file, you can view:
- Crash thread
- Exception type
- Call stack information
This method is suitable for developers for code-level debugging.
However, it has a limitation: it must be used in a Mac environment.
Second Method: Read System Logs via Device Tools
In testing environments, many devices are not connected to Xcode. In such cases, if logs still need to be viewed, device management tools are required.
In actual projects, I use Keymob Assistant to view device logs and crash reports.
This tool can directly read log files in iOS devices and organize them by category.
Using Keymob Assistant to View iOS Logs
Below is a common operational process.
Connect the Device
Preparation steps:
- Connect the iPhone or iPad using a USB data cable
- Open Keymob Assistant
- Wait for device recognition to complete
After the device is successfully connected, you can see the current device in the tool.
Enter the Log Center
In the left navigation, select:
File Management → Log Files
The right interface will display the log directory structure.
Here, you can see different categories of logs.
Common Log Directory Descriptions
In the log files interface, you can usually see several important directories.
CrashReporter
Stores application crash reports.
File extensions are typically:
.ips
.synced
Logs / Apple
System core logs.
Mainly records system component runtime information.
Diagnostics
Performance diagnostic data, such as system monitoring records.
WiFi
Wireless network connection records.
These logs can sometimes be used to troubleshoot network issues.
View Application Crash Reports
When analyzing an application crash, you can go to:
CrashReporter
This will list the crash log files on the device.
Crash logs are usually named according to the following convention:
[Application Name]-[Date]-[Time].ips
For example:
Twitter-2025-03-27-140847.ips
Using this naming convention, you can quickly find crash records for the corresponding time.
Troubleshooting Case
During a testing process, a tester reported:
“The app occasionally crashes when entering the video page.”
The troubleshooting process was roughly as follows:
Step 1: Export crash logs from the device.
Step 2: View the logs in CrashReporter for the corresponding time.
Step 3: Found in the call stack that the crash occurred in the video decoding module.
Further code analysis revealed:
The player initialization did not properly handle certain video formats.
After fixing and retesting, the issue disappeared.
Combined Use of Logs and Crash Reports
Viewing crash reports alone sometimes provides incomplete information.
It is usually necessary to combine:
- Real-time logs
- System logs
- Crash reports
This way, the complete runtime process at the time of the app crash can be reconstructed.
For example:
Real-time logs can show the operational flow before the crash, while crash reports record the final exception location.
Viewing iOS device logs and crash reports is a very important task in app development and testing. By combining development tools and device log tools, you can more comprehensively obtain device runtime information and quickly locate application issues.
Reference link: https://keymob.com/tutorial/zh/16/16.html