[Solved] How to use advance function in swift with three parameters?

by


That function increments the start index by n positions, but not
beyond the end index.

Example: You want to truncate strings to a given maximal length:

func truncate(string : String, length : Int) -> String {
    let index = advance(string.startIndex, length, string.endIndex)
    return string.substringToIndex(index)
}

println(truncate("fooBar", 3)) // foo
println(truncate("fo", 3))     // fo

In the first call, the start index is incremented by 3 positions,
in the second example only by two. With

let index = advance(string.startIndex, length)

the second call would crash with a runtime exception, because
a string index must not be advanced beyond the end index.

solved How to use advance function in swift with three parameters?