I was able to connect everything together in File's Owner just fine and I am getting no errors. Just warnings of
" method definition for '-buttonPressed:' not found" and
" incomplete implementation of class 'HelloWorld003ViewController'"
Those two warnings are extremely important, and your program will not work until they are fixed.
You should immediately enable the build option Treat Warnings As Errors (enter the words
treat warnings in the build settings search box). The default for this setting is disabled, which is more appropriate for experienced developers. Beginners often need the added discipline, especially if their default response to warnings is to ignore them.
If you're not going to enable the build setting, then you must change the way you deal with warnings. Do Not Ignore Any Warning.
The reason it's only a warning is because it's not actually a compile-time error. Objective-C as a language has certain things it can never determine at compile-time, only at run-time. For those, the compiler emits warnings, not errors. The compiler itself has no way to tell if you are an experienced developer or a beginner.
EDIT:
I also want to commend you for post #5. It is a fine example of how to ask a question that can be answered without a lot of back and forth.
You gave the console output messages, which provides information about what actually caused the program's failure.
You gave the source code for the area that was causing the problem.
You gave the compiler's error and warning messages, which helps narrow down where to look in the source.