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Application URL not opening in Facebook Browser on iOS



The Application URL below is not opening in the in-app Facebook browser (through Facebook messenger) on iOS.

Error Messages

The application does not load. Blank screen is displayed.

Steps to Reproduce

Open the Mashup URLs in in-app Facebook browser (through Facebook messenger) for iOS.

Root Cause

The gadget code did not have a check for handling the Facebook in app browser which is not supported

Mashup has a logic in mashup (html) and at PRPC level to check for valid browsers. In mashup html just for Safari there is an extra code path to solve the cross-domain cookie issue.
All these check is done using “user-agent” string that comes as part of the request header from the client. In this case for “Facebook In app browser on IOS” the user-agent string is totally different with “AppleWebKit” which is not checked in any of the existing browser check code both at mashup html and at PRPC. Hence the page returns empty without loading any content.


Include this new user agent string “AppleWebKit” both at mashup and at PRPC.

Note: This is added user-agent string in the Web-Login html rule and bypassed all these browser checks that was done at the decision table and packaged in “Ruleset:01-01-01” ruleset.

User agent string is very important on how uniquely it identifies each device to take separate code path basis on this.

 Code Changes:

1.    Mashup HTML Code - Application_FaceBook_Final.html:
Include the new user agent for this type of browser "AppleWebKit"

function myFunction(prpcHostName){
                                                var ua = navigator.userAgent;
                                                if((ua.indexOf("Trident") == -1) && (ua.indexOf("Firefox") == -1) && (ua.indexOf("Chrome") == -1) && ((ua.indexOf("Safari") != -1) || (ua.indexOf("AppleWebKit") != -1))){
                                                                if(document.cookie.indexOf("redirected=true") != -1){

2.    PRPC – Web-Login HTML rule:
Include the new user agent string “AppleWebKit”

                String userAgentString = pega_desktop_httprequestheader.pyGetUserAgent(tools);
                if(!userAgentString.contains("Trident") && !userAgentString.contains("Firefox") && !userAgentString.contains("Chrome") &&  (userAgentString.contains("Safari") || userAgentString.contains("AppleWebKit")))

3.    PRPC – IsUnsupportedOS Decision Table rule:
Modify the rule to bypass this check



Published October 21, 2016 - Updated October 8, 2020

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