Xcode does't print any debug logs after Attach to Process by PID or Name

Question

I use Xcode Version 10.2

Normal app debug print logs as expected, but when I want to test some delegate like

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
(NSDictionary *)launchOptions

I attach to process by PID or name option from Debug menu

Debug works as expected but in log windows is empty

Expected result: Show logs in debug after Attach to Process by PID or Name

Answer 1

This is not possible with lldb.

Redirecting a process' stdout & stderr is not the sort of thing a debugger should do by default, since the debugger has no way of knowing whether the process you are attaching to was part of a pipeline or for some other reason wanted its stdout to stay where it was.

It isn't offered as an option because there isn't a robust supported way to redirect the stdout/stderr of a process from the outside.