Swift 4 / Xcode 9.4 support

Merge pull request #4 from WorldDownTown/swift4

Swift 4 / Xcode 9.4 support

Update method interface

• Update method interface.

// Triggers a impact feedback between small, light user interface elements. (`UIImpactFeedbackStyle.light`)
TapticEngine.impact.feedback(.light)

// Triggers a impact feedback between moderately sized user interface elements. (`UIImpactFeedbackStyle.medium`)
TapticEngine.impact.feedback(.medium)

// Triggers a impact feedback between large, heavy user interface elements.  (`UIImpactFeedbackStyle.heavy`)
TapticEngine.impact.feedback(.heavy)

// Triggers a selection feedback to communicate movement through a series of discrete values.
TapticEngine.selection.feedback()

// Triggers a notification feedback, indicating that a task has completed successfully. (`UINotificationFeedbackType.success`)
TapticEngine.notification.feedback(.success)

// Triggers a notification feedback, indicating that a task has produced a warning. (`UINotificationFeedbackType.warning`)
TapticEngine.notification.feedback(.warning)

// Triggers a notification feedback, indicating that a task has failed. (`UINotificationFeedbackType.error`)
TapticEngine.notification.feedback(.error)

// Prepare a impact feedback for `UIImpactFeedbackStyle.light`.
TapticEngine.impact.prepare(.light)

// Prepare a selection feedback.
TapticEngine.selection.prepare()

// Prepare a notification feedback.
TapticEngine.notification.prepare()

Initial Release

Initial version. Check my README.md please.