[Issue 16] Fix corner radius bug (#17)

Author: Mark Pospesel

Sources/YBottomSheet/BottomSheetController.swift

@@ -46,7 +46,6 @@ public class BottomSheetController: UIViewController {
         let view = UIView()
         view.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMinXMinYCorner]
         view.backgroundColor = .systemBackground
-        view.backgroundColor = .systemBackground
         return view
     }()
     /// Bottom sheet drag indicator view.
@@ -178,6 +177,16 @@ private extension BottomSheetController {
     func build(_ subview: UIView, title: String) {
         contentView.addSubview(subview)
         subview.constrainEdges()
+
+        if let backgroundColor = subview.backgroundColor,
+           backgroundColor.rgbaComponents.alpha == 1 {
+            // use the subview's background color for the sheet
+            sheetView.backgroundColor = backgroundColor
+            // but we have to set the subview's background to nil or else
+            // it will overflow the sheet and not be cropped by the corner radius.
+            subview.backgroundColor = nil
+        }
+
         indicatorView = DragIndicatorView(appearance: appearance.indicatorAppearance ?? .default)
         indicatorContainer.addSubview(indicatorView)
 

Tests/YBottomSheetTests/BottomSheetControllerTests.swift

@@ -343,6 +343,51 @@ final class BottomSheetControllerTests: XCTestCase {
         sut.simulateTapCloseButton()
         XCTAssertTrue(sut.isDismissed)
     }
+
+    func test_backgroundColor_copiedFromChild() {
+        let color: UIColor = .systemPurple
+        let view = UIView()
+        view.backgroundColor = color
+        let sut = makeSUT(view: view)
+        let traits = UITraitCollection(preferredContentSizeCategory: .large)
+        XCTAssertNotNil(view.backgroundColor)
+
+        sut.loadViewIfNeeded()
+
+        XCTAssertEqual(
+            sut.sheetView.backgroundColor?.resolvedColor(with: traits),
+            color.resolvedColor(with: traits)
+        )
+        XCTAssertNil(view.backgroundColor)
+    }
+
+    func test_clearBackgroundColor_notCopiedFromChild() {
+        let view = UIView()
+        view.backgroundColor = .clear
+        let sut = makeSUT(view: view)
+        let traits = UITraitCollection(preferredContentSizeCategory: .large)
+
+        sut.loadViewIfNeeded()
+
+        XCTAssertEqual(
+            sut.sheetView.backgroundColor?.resolvedColor(with: traits),
+            UIColor.systemBackground.resolvedColor(with: traits)
+        )
+    }
+
+    func test_nilBackgroundColor_notCopiedFromChild() {
+        let view = UIView()
+        view.backgroundColor = nil
+        let sut = makeSUT(view: view)
+        let traits = UITraitCollection(preferredContentSizeCategory: .large)
+
+        sut.loadViewIfNeeded()
+
+        XCTAssertEqual(
+            sut.sheetView.backgroundColor?.resolvedColor(with: traits),
+            UIColor.systemBackground.resolvedColor(with: traits)
+        )
+    }
 }
 
 private extension BottomSheetControllerTests {