[iOS] Remove log which may cause infinite loop printing invalid object.
diff --git a/ios/sdk/WeexSDK/Sources/Utility/WXUtility.m b/ios/sdk/WeexSDK/Sources/Utility/WXUtility.m
index 3e2eb17..a8307bc 100644
--- a/ios/sdk/WeexSDK/Sources/Utility/WXUtility.m
+++ b/ios/sdk/WeexSDK/Sources/Utility/WXUtility.m
@@ -422,7 +422,6 @@
         return true;
     }
     if (![string isKindOfClass:[NSString class]]) {
-        WXLogError(@"%@ is not a string", string);
         return true;
     }
     if ([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] length] == 0) {