Merge pull request #128 from kazuhiro4949/feature/willbegin_delegate

call delegate only when scrolling another page
kazuhiro4949 · Jan 5, 2021 · 1ccc9fa · 1ccc9fa
2 parents 4ca9e09 + 9a9de75
commit 1ccc9fa
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Showing 2 changed files with 68 additions and 5 deletions.
diff --git a/Sources/PagingContentViewController.swift b/Sources/PagingContentViewController.swift
@@ -51,6 +51,7 @@ public protocol PagingContentViewControllerDelegate: class {
 
 
     /// Tells the delegate when the view controller is trying to start paging the content.
+    /// If it is the same page as the current, this delegate is not called.
     ///
     /// - Parameters:
     ///   - viewController: The view controller object in which the scrolling occurred.
@@ -59,6 +60,7 @@ public protocol PagingContentViewControllerDelegate: class {
     func contentViewController(viewController: PagingContentViewController, willBeginPagingAt index: Int, animated: Bool)
 
     /// Tells the delegate when the view controller is trying to finish paging the content.
+    /// If it is the same page as the current, this delegate is not called.
     ///
     /// - Parameters:
     ///   - viewController: The view controller object in which the scrolling occurred.
@@ -67,6 +69,7 @@ public protocol PagingContentViewControllerDelegate: class {
     func contentViewController(viewController: PagingContentViewController, willFinishPagingAt index: Int, animated: Bool)
 
     /// Tells the delegate when the view controller was finished to paging the content.
+    /// If it is the same page as the current, this delegate is not called.
     ///
     /// - Parameters:
     ///   - viewController: The view controller object in which the scrolling occurred.
@@ -204,7 +207,11 @@ public class PagingContentViewController: UIViewController {
 
 
     private func scroll(to page: Int, needsCallAppearance: Bool, animated: Bool, completion: ((Bool) -> Void)? = nil) {
-        delegate?.contentViewController(viewController: self, willBeginPagingAt: leftSidePageIndex, animated: animated)
+        let isScrollingToAnotherPage = leftSidePageIndex != page
+
+        if isScrollingToAnotherPage {
+            delegate?.contentViewController(viewController: self, willBeginPagingAt: leftSidePageIndex, animated: animated)
+        }
 
         if needsCallAppearance {
             appearanceHandler.beginDragging(at: leftSidePageIndex)
@@ -213,16 +220,22 @@ public class PagingContentViewController: UIViewController {
         loadPagesIfNeeded(page: page)
         leftSidePageIndex = page
 
-        delegate?.contentViewController(viewController: self, willFinishPagingAt: leftSidePageIndex, animated: animated)
+        if isScrollingToAnotherPage {
+            delegate?.contentViewController(viewController: self, willFinishPagingAt: leftSidePageIndex, animated: animated)
+        }
+
         move(to: page, animated: animated) { [weak self] (finished) in
             guard let _self = self, finished else { return }
 
             if needsCallAppearance {
                 _self.appearanceHandler.stopScrolling(at: _self.leftSidePageIndex)
             }
 
+            if isScrollingToAnotherPage {
+                _self.delegate?.contentViewController(viewController: _self, didFinishPagingAt: _self.leftSidePageIndex, animated: animated)
+            }
+
             completion?(finished)
-            _self.delegate?.contentViewController(viewController: _self, didFinishPagingAt: _self.leftSidePageIndex, animated: animated)
         }
     }
 

diff --git a/Tests/PagingContentViewControllerTests.swift b/Tests/PagingContentViewControllerTests.swift
@@ -349,18 +349,63 @@ extension PagingContentViewControllerTests {
         UIApplication.shared.keyWindow?.rootViewController = self.pagingContentViewController
 
         XCTAssertNil(delegate.willBeginPagingAt_args)
+        XCTAssertNil(delegate.willFinishPagingAt_args)
+        XCTAssertNil(delegate.didFinishPagingAt_args)
         XCTAssertNil(self.contentAppearanceHandler.beginDragging_args)
         XCTAssertNil(self.contentAppearanceHandler.stopScrolling_args)
 
         XCUIDevice.shared.orientation = .landscapeLeft
 
-        XCTAssertNotNil(delegate.willBeginPagingAt_args)
+        XCTAssertNil(delegate.willBeginPagingAt_args)
+        XCTAssertNil(delegate.willFinishPagingAt_args)
+        XCTAssertNil(delegate.didFinishPagingAt_args)
         XCTAssertNil(self.contentAppearanceHandler.beginDragging_args)
         XCTAssertNil(self.contentAppearanceHandler.stopScrolling_args)
         expectation.fulfill()
 
         wait(for: [expectation], timeout: 1)
     }
+
+    func test_ScrollingTheSamePage_callingDelegate() {
+        let expectation = XCTestExpectation(description: "finish reloadData")
+        let dataSource = PagingContentVcDataSourceSpy()
+        let delegate = PagingContentVcDelegateSpy()
+        pagingContentViewController?.dataSource = dataSource
+        pagingContentViewController?.delegate = delegate
+        pagingContentViewController?.loadViewIfNeeded()
+        pagingContentViewController?.reloadData(with: 3) { [unowned self] in
+            self.pagingContentViewController?.scroll(to: 3, animated: false)
+
+            XCTAssertEqual(delegate.willBeginPagingAt_callCount, 0)
+            XCTAssertEqual(delegate.willFinishPagingAt_callCount, 0)
+            XCTAssertEqual(delegate.didFinishPagingAt_callCount, 0)
+
+            expectation.fulfill()
+        }
+
+        wait(for: [expectation], timeout: 0.2)
+    }
+
+    func test_ScrollingAnotherPage_callingDelegate() {
+        let expectation = XCTestExpectation(description: "finish reloadData")
+        let dataSource = PagingContentVcDataSourceSpy()
+        let delegate = PagingContentVcDelegateSpy()
+        pagingContentViewController?.dataSource = dataSource
+        pagingContentViewController?.delegate = delegate
+        pagingContentViewController?.loadViewIfNeeded()
+        pagingContentViewController?.reloadData(with: 3) { [unowned self] in
+            self.pagingContentViewController?.scroll(to: 4, animated: false) { _ in
+
+                XCTAssertEqual(delegate.willBeginPagingAt_callCount, 1)
+                XCTAssertEqual(delegate.willFinishPagingAt_callCount, 1)
+                XCTAssertEqual(delegate.didFinishPagingAt_callCount, 1)
+
+                expectation.fulfill()
+            }
+        }
+
+        wait(for: [expectation], timeout: 0.2)
+    }
 }
 
 
@@ -416,19 +461,24 @@ class PagingContentVcDelegateSpy: NSObject, PagingContentViewControllerDelegate
         didEndManualScrollOn_args = (viewController, index)
     }
 
+    var willBeginPagingAt_callCount = 0
     var willBeginPagingAt_args: (PagingContentViewController, Int, Bool)?
     func contentViewController(viewController: PagingContentViewController, willBeginPagingAt index: Int, animated: Bool) {
         willBeginPagingAt_args = (viewController, index, animated)
+        willBeginPagingAt_callCount += 1
     }
 
+    var willFinishPagingAt_callCount = 0
     var willFinishPagingAt_args: (PagingContentViewController, Int, Bool)?
     func contentViewController(viewController: PagingContentViewController, willFinishPagingAt index: Int, animated: Bool) {
         willFinishPagingAt_args = (viewController, index, animated)
+        willFinishPagingAt_callCount += 1
     }
-
+    var didFinishPagingAt_callCount = 0
     var didFinishPagingAt_args: (PagingContentViewController, Int, Bool)?
     func contentViewController(viewController: PagingContentViewController, didFinishPagingAt index: Int, animated: Bool) {
         didFinishPagingAt_args = (viewController, index, animated)
+        didFinishPagingAt_callCount += 1
     }
 }