Compile error on newest ChartsDemo-iOS project

[JCMcLovin]

• I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

I downloaded the latest version of the library (4.1) and attempted to run the ChartsDemo-iOS-Swift project.

What did you expect to happen?

I expected it to build and run.

What happened instead?

I got a compile error. In DataApproximator+N.swift, Xcode complains about the func reduceWithDouglasPeukerN(_ points: [CGPoint], resultCount: Int) -> [CGPoint] saying:

Value of type 'EnumeratedSequence<[CGPoint]>' has no member 'compactMap'

Charts Environment

Charts version/Branch/Commit Number: 4.1/Master/#3370
Xcode version: 9.2
Swift version: 4.0.3
Platform(s) running Charts: iOS 11.2
macOS version running Xcode: High Sierra 10.13.3

Demo Project

https://github.com/danielgindi/Charts/tree/master/ChartsDemo-iOS

[thierryH91200]

see #3372
try with
Xcode version : 9.3
Swift version: 4.1

[liuxuan30]

it's done.

 - 3.1.1 (2018-04-03 01:22:23 UTC)

[suhaspathak]

It's not support Xcode 9.2. need to update Xcode version.