From 423f2acd63875f672e7268c27d7fb9d2e842925d Mon Sep 17 00:00:00 2001
From: Evan DeLaney <evan@fishhook.com>
Date: Thu, 19 Dec 2019 11:25:11 -0500
Subject: [PATCH] Improve API contract

---
 Sources/PagerTabStripViewController.swift | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Sources/PagerTabStripViewController.swift b/Sources/PagerTabStripViewController.swift
index 9aedb7d6..329b6972 100644
--- a/Sources/PagerTabStripViewController.swift
+++ b/Sources/PagerTabStripViewController.swift
@@ -42,9 +42,11 @@ public protocol PagerTabStripIsProgressiveDelegate: PagerTabStripDelegate {
     func updateIndicator(for viewController: PagerTabStripViewController, fromIndex: Int, toIndex: Int, withProgressPercentage progressPercentage: CGFloat, indexWasChanged: Bool)
 }
 
+public typealias ViewControllerIndicatorInfoProvider = UIViewController & IndicatorInfoProvider
+
 public protocol PagerTabStripDataSource: class {
 
-    func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [UIViewController]
+    func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [ViewControllerIndicatorInfoProvider]
 }
 
 // MARK: PagerTabStripViewController
@@ -177,7 +179,7 @@ open class PagerTabStripViewController: UIViewController, UIScrollViewDelegate {
 
     // MARK: - PagerTabStripDataSource
 
-    open func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [UIViewController] {
+    open func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [ViewControllerIndicatorInfoProvider] {
         assertionFailure("Sub-class must implement the PagerTabStripDataSource viewControllers(for:) method")
         return []
     }
@@ -381,8 +383,6 @@ open class PagerTabStripViewController: UIViewController, UIScrollViewDelegate {
         guard !viewControllers.isEmpty else {
             fatalError("viewControllers(for:) should provide at least one child view controller")
         }
-        viewControllers.forEach { if !($0 is IndicatorInfoProvider) { fatalError("Every view controller provided by PagerTabStripDataSource's viewControllers(for:) method must conform to IndicatorInfoProvider") }}
-
     }
 
     private var pagerTabStripChildViewControllersForScrolling: [UIViewController]?