Custom http header on UIWebView requests causing back button to break - ios

Question

I'm using the following code to inject a custom http header into my UIWebView requests:
func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool {
let headerFields = request.allHTTPHeaderFields
var headerIsPresent = contains(request.allHTTPHeaderFields?.keys.array as [String], "X-Test-App")
if headerIsPresent || navigationType == UIWebViewNavigationType.Other {
return true
} else {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
dispatch_async(dispatch_get_main_queue(), {
let url = request.URL
var newRequest: NSMutableURLRequest = request as NSMutableURLRequest
// set new header
newRequest.addValue("MyValue", forHTTPHeaderField: "X-Test-App")
// reload the request
self.webView.loadRequest(newRequest)
})
})
return false
}
}
The problem is that the back button history is not being kept. So if I click like 3 requests deep. When hitting back, it will only go to the previous page and then hitting back again will result in it going back to the page you just went back from. It's basically an endless loop between the 2 most recent requests. Any idea how I can modify the above code to be able to keep the entire web history and allow the back/forward buttons to function as expected?

Answer 1

The problem is that UIWebView's built-in goBack() only goes back 1 page, but by intercepting the loadRequest and replacing it with a new request, webView is seeing this as a new, second item in the history. So more work will be required to combine 1) UIWebview built-in history, 2) UIWebView goBack(), and 3) this method of intercepting load requests.
The button calling goBack() could just call goBack() twice-- if in the same code block, I assume UIWebView would jump to the second item in the history. But this is fragile in other ways, not recommended.
You could create a stack of unmodified requests. Set up an array, and call append() to add the unmodified request before creating the new one. But first, for every unmodified request, check if it's the lastObject in the array. If so, they probably want the one before that, so remove it from the end of the array and create a modified request with the new lastObject.