Question 1

How do I trace a specific object instance with Xtrace?

Accepted Answer

Use the category method [instance xtrace] to trace all calls to that particular instance. You can also stop tracing with [instance notrace], and instance tracing takes precedence over class-based filtering, as explained in the README.

Question 2

Does Xtrace work on ARM64 iPhones?

Accepted Answer

No, Xtrace does not work on the ARM64 ABI. The README explicitly states this and recommends rebuilding for 32 bits. For 64-bit builds, it has stack frame complications, especially with struct types.

Question 3

Xtrace vs Instruments for Objective-C debugging?

Accepted Answer

Xtrace provides real-time, detailed method call logging and aspect-oriented features for runtime introspection, while Instruments offers broader system-level profiling and performance analysis. Xtrace is better for fine-grained debugging, but Instruments is more comprehensive for production tuning.

Question 4

How can I filter methods to trace only certain selectors?

Accepted Answer

Use [Xtrace includeMethods:@"regex"] and [Xtrace excludeMethods:@"regex"] to set regular expression filters. These are applied during class swizzling, allowing you to focus on specific method calls, such as excluding varargs methods.

Question 5

Can Xtrace modify the return value of a method?

Accepted Answer

Yes, through after callbacks in a delegate. By implementing a callback that matches the method signature, you can intercept and return a new value, effectively modifying behavior, as shown in the aspect-oriented examples.

Question 6

Is Xtrace still maintained and updated?

Accepted Answer

The project is superseded by SwiftTrace for Swift development, and the README suggests it's stable but not actively enhanced. For Objective-C, it may receive occasional fixes, but major updates are unlikely.

Xtrace

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