I want to concatenate a string, and I do this:
var text: String! .... text = "hello" text += "! How r you?" But I got the following error:
cannot convert value of type 'String!' to expected argument type 'inout String' text += "!" ^~~~
How can I fix it? Thanks
If you want to append something to an optional, but only if it's not nil, you should put a question mark after the variable's name.
text? += "appended text" 
text? += "! How r you?"
You have to define the variable without the exclamation mark, like that :
var text: String = "" text = "hello" text += "! How r you?" Or shorter in function of the context:
var text: String = "hello" text += "! How r you?" You can get it by doing this
var text = "Hello!" as! String text = text + " How are you?" Hope it helps.
When handling exclamation points in Swift, you have to remember that trying to use ! to access a nonexistent optional value triggers a runtime error.
If an optional has a value, it is considered to be “not equal to nil”. So you have to check this before you can access to its underlying value:
if text != nil { text += "! How are you?" } 
var text: String!tovar text = ""