BBCBasic

Takes a few seconds to work out how to create a NEW BASIC file, but does what it says. Main niggle is the lack of any feature / means to convert Carriage Returns to Line Feeds and vice versa, to permit code blocks to be pasted in from the Web, Apple's Note app, a text editor, ... . Limiting any copy-n-pastes to a single line.

Generally this app is amazing. The only issue is ensuring you disable smart punctuation in the keyboard system setting on your iPad if the " character is playing up.

This is the most powerful implementation of Basic on iOS by miles. It's also completely free, with no ads; it doesn't harvest your data; and it doesn't even take up too much space on your device. You probably won't become a Silicon Valley billionaire writing BBC Basic, but there's no better way to (a) learn programming and (b) write useful programs of your own to do jobs you can't find an app for. There's lots of documentation online to help you get started with the BBC Basic language. A few minor points to be aware of: (1) The app itself takes a bit of getting used to. It isn't that the user interface is bad, but it's quite different from most other iOS apps. (2) This is an implementation of the BBC Basic language, not a BBC Micro emulator. Old 1980s programs written in pure Basic will almost certainly run, although you might need to make some minor changes (e.g. a few COLOUR statements to get the palette looking the same) and they'll be much faster; but anything that relies on the particular processor or particular memory addresses definitely won't. Don't expect to be able to run commercial BBC Micro software! (3) Other modern structured Basics are mostly derived from Microsoft's QBasic, but this one isn't. Straightforward differences of syntax won't cause anyone much trouble—it's easy to put ENDPROC instead of END SUB. But there are more subtle differences (parameters in BBC Basic are passed by value unless you specifically ask for pass by reference, local variables have dynamic scope instead of lexical scope, etc.) that won't always stop your programs running but can sometimes cause awkward bugs. So if you're used to a Microsoft-style Basic you should read up on how BBC Basic does things. (You don't need to worry about these issues at all if you're new to programming!)