UIKit: Initial first responder?

Question

When an app launches, what is the initial first responder?

According to the UIKit docs the first responder can be set with the becomeFirstResponder message. However, if this message isn't sent, what is the initial first responder? The UIApplication? The key window?

Also, is there a property anywhere which points to the current first responder?

Answer 1

In both MacOS & iOS, each window has their own UIResponder (or, to be more precise, each window IS a UIResponder -- UIWindow descends from UIResponder), which means that each window can have their own first responder. On MacOS, there can be many open windows (each one with a first responder) and under iOS, there is usually one UIWindow displayed at any one time.

Each window will have a first responder (whether the window itself, or a text field which is receiving keyboard events, or whatever). You can query each window's responder chain by walking down each of them via the " nextResponder " API .

I'm probably simplifying things a little too much but for the sake of a nice, simple summarized answer I hope this helps. Here is more information about the iOS Responder chain , which shows how an initial view (eg the first responder) gets an event and if it can't handle it, the event get passed up to parent views, to the window and to the application.