When I create a new single App project the Main interface is preset with "Main". What is the difference between that "Main" and Main.storyboard?
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Christoph
They (basically) mean the same thing.
"Main.storyboard" is the actual name of the storyboard file. This file is similar to your source code files, in that it is "compiled" into another file when you build your app in Xcode. This other file has the same name "Main" but a different extension.
Since the actual compiled file extension is an incidental detail of the build process, Xcode allows you to specify just the file name without extension in the General settings tab.
I believe you can specify a full name there (e.g. "Main.storyboard"), and Xcode will understand what you mean and discard the extension. However, it's more usual just to specify the base file name, as offered to you in the popup menu on that field.
main is what appears afterlaunchScreen.storyboard, which is what your app initially displays when the app first runs/comes back.
launchScreen.storyboard helps to give the user something to look at while the code begins to run - think of it as the opening act until the main act comes out on stage to perform.
