[RandallBrown]

Obviously it depends heavily on what you're doing in your app and where that string is coming from.

Is it a hard coded string that will never change? Force unwrapping is probably appropriate.

Is it based on user input? Then you should probably tell the user the string they entered isn't a URL.

[saagarjha]

Right, and in that case it's pretty clear how errors can occur and what you should do to handle it.