"css-display-none" type content blocker actions do not work in iOS 10.3.1

Originator:kane.cheshire
Number:rdar://31779540 Date Originated:24 April 2017
Status:Open Resolved:
Product:iOS + SDK Product Version:Safari Services
Classification:Serious bug Reproducible:Always
 
Running a simple "css-display-none" content blocker in iOS 10.3.1 does not work. The `SFContentBlockerManager` method `reloadContentBlocker` fails to reload the content blocker with an error stating that the content blocker is empty, and the rules are ignored when running Safari.

This is the error: 

Error Domain=_WKUserContentExtensionsDomain Code=3 "(null)" UserInfo={NSHelpAnchor=Extension compilation failed: Empty extension.

Running exactly the same simple content blocker in iOS 9 works fine and `reloadContentBlocker` reloads without an error.

This is the content blocker json:
[
    {
        "action": {
            "type": "css-display-none",
            "selector": "a"
        },
        "trigger": {
            "url-filter": ".*",
            "if-domain": ["macrumors.com"]
        }
    }
]

Ensure you call ``SFContentBlockerManager.reloadContentBlocker` AFTER enabling the content blocker in Safari settings or you will not get an error.

Steps to Reproduce:
1: create a content blocker with the following content blocker json:
[
    {
        "action": {
            "type": "css-display-none",
            "selector": "a"
        },
        "trigger": {
            "url-filter": ".*",
            "if-domain": ["macrumors.com"]
        }
    }
]
2: Run on a compatible device running iOS 9, enable the content blocker and call `SFContentBlockerManager.reloadContentBlocker`
3: Observe that the rules are working for iOS 9 when visiting MacRumors (all the links are missing)
4: Run the content blocker on a compatible device running iOS 10.3.1, enable the content blocker and call `SFContentBlockerManager.reloadContentBlocker`
5: Observe that the call to reload fails and the rules are no longer observed when visiting MacRumors.

Expected Results:
The content blocker should reload and the rules should be observed by Safari.

Actual Results:
The content blocker fails to reload and the rules are not observed by Safari.

Version:
iOS 10.3.1 14E304

Notes:


Configuration:
iPhone 7 Plus Black 128GB

Comments

This wasted 2 hours of my life. Xcode 8.3.3 ships with the 10.3.1 simulator, which still has this bug. The result was that none of my css-display-none blocker extension rules were applying in the simulator and I had no idea why.

Tested now on my actual 10.3.2 phone and they worked just fine. Glad I found this.

By pertinax at July 3, 2017, 2:03 a.m. (reply...)

I've been fighting with this for a month.

Edit: tried it with iOS 10.2 and works perfectly.

Edit 2: It has been fixed in iOS 10.3.2

By alex.bartis at April 26, 2017, 6:42 p.m. (reply...)

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