How to debug iOS 8 extensions with NSLog?

- (void)viewDidLoad
{
    NSLog(@"%s", __func__);
    // ...
}

in viewDidLoad of an iOS 8 extension. the NSLog outputs nothing in Xcode. NSLog works as usual in the container app though.

How can I get output from debug messages from an extension?

Solution 1:

1. Debugging works for app extensions.
2. It works on simulator too.
3. If your app ext crashes in the simulator, you may find it is not easy to restart your app ext. Restarting your simulator is a quick solution.

4. Steps to debug an app extension:

   1. Run the container app. In this step, Xcode uploads the container app and app extension to the device or simulator.

   2. Stop the container app. This step is important when you debug in simulator. If you don't do it, Xcode will tell you the simulator is in use.

   3. In Xcode, press menu Debug -> Attach to Process -> By Process Identifer (PID) or Name..., input the app ext's identifier, e.g. com.abc.ContainerApp.MyExtension, to start debugging. Don't forget to set break points. (Update on Aug 25, 2014: you can input MyExtension(your extension's name) directly.)

   4. In the device or simulator, open your app extension.

Updates on Aug 23, 2014:

I found the debugging steps above do not work well on Xcode 6 beta 6 with iOS 8 SDK beta 5 on the simulator.

Solution:

1. Run your extension in the simulator.
2. Xcode menu Debug -> Attach to Process -> Choose "MyExtension(your extension's name)" in System section in the menu.

The breakpoints work. But I don't know why logs do not show in the output window.

Solution 2:

I'm having this problem too. It works for me if you go in your Simulator under the menu Debug -> Open System Log...

From here you can see all the logs of the iPhone Simulator (included your extension's logs).