How do I concatenate strings in Swift?

How to concatenate string in Swift?

In Objective-C we do like

NSString *string = @"Swift";
NSString *resultStr = [string stringByAppendingString:@" is a new Programming Language"];

or

NSString *resultStr=[NSString stringWithFormat:@"%@ is a new Programming Language",string];

But I want to do this in Swift-language.