Question about making a variable non-conditional from a point onwards

Question

GabrielZ OP

Created Jul ’20

Replies 1

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Participants 2

I am still fairly new to Swift, so please bear with me.

I have this piece of code:

Code Block var win_name : String? = winInfo[kCGWindowName as String] as? String
if ( win_name == nil )
{
win_name = winInfo[kCGWindowOwnerName as String] as? String
}
if ( win_name == nil )
{
	 win_name = "???"
}
// from here on, we know win_name is non-nil

After the last line, there are many more lines where I need to do access win_name lots of times. Each time I have to write win_name! .

Is there a way to tell the compiler that after line 10, win_name is always non-nil, so that I don't have to force-unwrap it every time?

I could use something like

Code Block guard let win_name_nonnil = win_name else { return }

at line 10, but IMHO that would make the code after line 10 even uglier.

Insights will be highly appreciated.

Answered by OOPer in 620399022

In your case, nil-coalescing operator ?? would work.

Code Block let win_name : String = winInfo[kCGWindowName as String] as? String
		?? winInfo[kCGWindowOwnerName as String] as? String
		?? "???"

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Answer 1

OOPer OP

Jul ’20

Accepted Answer

In your case, nil-coalescing operator ?? would work.

Code Block let win_name : String = winInfo[kCGWindowName as String] as? String
		?? winInfo[kCGWindowOwnerName as String] as? String
		?? "???"

1