[iOS] fix image can not show when use xcode12 build
diff --git a/ios/sdk/WeexSDK/Sources/Display/WXLayer.m b/ios/sdk/WeexSDK/Sources/Display/WXLayer.m
index d293d6d..48cb022 100644
--- a/ios/sdk/WeexSDK/Sources/Display/WXLayer.m
+++ b/ios/sdk/WeexSDK/Sources/Display/WXLayer.m
@@ -26,6 +26,7 @@
 
 - (void)display
 {
+    [super display];
     [self.wx_component _willDisplayLayer:self];
 }