Confused by this snippet code

[lumiasaki]

In ChartViewBase.swift file, these is a snippet code like this:

/// returns the x-value at the given index
public func getXValue(index: Int) -> String!
{
if (_data == nil || _data.xValCount <= index)
{
return nil;
}
else
{
return _data.xVals[index];
}
}

I am not good at swift but I'm confused about the function's return type: String!, obviously, it may return nil.

I hope what I'm saying is clear enough...thx

[danielgindi]

That question is suitable for a Swift forum, or Stackoverflow, or just reading the Swift manual by Apple!
But to make long story short, a String! is an optional String (nullable) that will unwrap automatically, avoiding the need to user the ? operator for reading its value.