how to determine hangs in swiftui instruments

To determine hangs in SwiftUI using Instruments, you can utilize the new features in Xcode 16. Specifically, the Time Profiler instrument is useful for diagnosing performance problems by visualizing CPU usage in your code. Here's a step-by-step approach:

Record a Trace: Use the Time Profiler instrument to record a trace of your app's launch. This will help you visualize CPU usage and identify any long hangs during the initial launch.
Set Inspection Range: Focus on the hang interval by setting the inspection range to that specific portion of the trace. This allows you to narrow down the problem area.
Use the Flame Graph: Activate the new flame graph from the jump bar in Instruments. The flame graph provides a high-level overview of the trace execution, allowing you to spot issues at a glance. Execution intervals are weighted by the percentage of time they took in the trace, and sorted from left to right.
Analyze the Code: Look for functions that are taking up a significant amount of execution time. For example, if a load function is consuming nearly all of the execution time and is being called from a SwiftUI view body, it might indicate a problem.
Optimize the Code: If you find that assets are being loaded serially in a loop on the main thread, consider parallelizing the loading using a task group and moving the execution to the background.

For more detailed guidance, you can refer to the session What’s new in Xcode 16 (19:44) where these techniques are discussed.