Merge pull request #281 from heoblitz/fix/markDirty_error

Fix error when dynamically removing views

Author: lucdion

Sources/YogaKit/YGLayout.mm

@@ -227,11 +227,13 @@ - (void)markDirty {
   // the measure function. Since we already know that this is a leaf,
   // this *should* be fine. Forgive me Hack Gods.
   const YGNodeRef node = self.node;
-  if (!YGNodeHasMeasureFunc(node)) {
+  if (!YGNodeHasMeasureFunc(node) && self.numberOfChildren == 0) {
     YGNodeSetMeasureFunc(node, YGMeasureView);
   }
 
-  YGNodeMarkDirty(node);
+  if (YGNodeHasMeasureFunc(node)) {
+    YGNodeMarkDirty(node);
+  }
 }
 
 - (NSUInteger)numberOfChildren {

Tests/FlexLayoutTests/FlexLayoutTests.swift

@@ -26,5 +26,18 @@ final class FlexLayoutTests: XCTestCase {
 
         XCTAssertNil(weakView, "Creation of flex should not lead to retain cycle")
     }
+  
+    
+    func testRemoveViewDynamically() {
+        let rootFlexContainer = UIView()
+        rootFlexContainer.flex.addItem(UIView())
+        rootFlexContainer.flex.define { _ in }
+        rootFlexContainer.flex.layout()
+        
+        rootFlexContainer.subviews.forEach { $0.removeFromSuperview() }
+        rootFlexContainer.flex.markDirty()
+        rootFlexContainer.flex.layout()
 
+        XCTAssertTrue(rootFlexContainer.subviews.isEmpty)
+    }
 }